It is widely accepted in the rheumatology community that there is a “time window” for the treatment of RA, during which the disease is more likely to be controlled and the long-term trajectory of the disease can be altered. Many studies have shown that early treatment, for example within 3 months of onset, has a better prognosis than late treatment, and that intensive treatment within the early treatment window delays long-term structural damage. However, these data only indicate that early treatment is better than late treatment, but do not specify when the treatment time window ends. It is critical that there is a time limit on whether a time window exists for treatment of early RA. If a time window does exist, efforts need to be made to treat before the end of the time window and to focus on improving efficiency in treatment within the time window. Two large studies analyzed the relationship between initial symptom duration and good prognosis in terms of 1) sustained remission after discontinuation of DMARD, 2) sustained remission with or without DMARD application, and 3) reduced radiographic progression. The study found that symptom duration was not linearly related to good prognosis, and for all prognoses may reach a point where the benefit decreases when the duration of treatment is reduced. In particular, for the primary study endpoint of patients (sustained remission with discontinuation of DMARD), the treatment time window was within 14.9 weeks in the Leiden cohort and 19.1 weeks in the ESPOIR cohort. The authors were cautious in interpreting the relatively wide confidence intervals of 12.3-16 weeks in the Leiden cohort and 12.3-28 weeks in the ESPOIR cohort. On the surface, however, these data do seem to suggest that there is a stage at which treatment with DMARD for the first 6 months or even less can significantly improve long-term prognosis. The clinical and research implications of these data are significant. Timely diagnosis of new-onset RA in the clinic is difficult. Data from 10 European centers from 2009 to 2010 show that the median time from symptom onset to the patient’s visit to the rheumatologist is 24 weeks. Thus, many patients are already outside the treatment window by the time they are seen. The delay in diagnosis by rheumatologists is reflected in 3 main areas: 1) delay in the patient’s first visit to the general practitioner; 2) delay in the GP referring the patient to the rheumatologist; and 3) delay in the diagnosis of the patient by the rheumatologist specialist. The degree of delay in each of these components is largely influenced by the local healthcare environment, and reasonable measures to reduce delays in all 3 areas are likely to maximize prognosis. In areas where patient delays are predominant, public health campaigns should be conducted to explain why patients with RA are often delayed in seeking care and why many patients are unaware of RA, and to promote the risk factors for RA or the fact that their symptoms may manifest early in the disease and that treatment can improve long-term prognosis. This is especially important when the disease is mild and progresses slowly. When there is a delay in primary care, patients need to be seen more quickly. Patient education in general practice and enabling general practitioners to refer patients with synovitis to a rapid access “early arthritis recognition clinic” or to get a faster appointment to identify or exclude synovial inflammation. A potential mechanism for the existence of a time window is the different nature of synovitis (different cellular and cytokine milieu) within the time window, and therefore a better response to treatment. In addition, the amount of synovitis varies, and once the synovium reaches a certain amount the response to treatment is not as good as before. There are limited data on the difference in synovial pathology between early RA and long course RA, although some data suggest that it may be different in the early stages. Further data are needed in this area to suggest whether treatment is administered within the time window. There are other explanations for the existence of a time window, where patients with early onset of symptoms can be treated early, and when symptoms are complete, then treatment is late. the Leiden cohort study showed that progressive onset at disease onset and small joint involvement were independently associated with delayed diagnosis by rheumatologists. In contrast, those with rapid onset and large joint involvement were treated early and had an optimized natural course, so the analysis of cohort data may suggest a time window unless patients are satisfied with alternative modes of onset and health care addresses other factors causing delayed diagnosis. If we do believe that there is a time window for treatment of RA, the study by van Nies et al. suggests that it may begin with the patient’s first “musculoskeletal symptoms”. Identifying the earliest symptoms “associated” with RA is challenging. For example, when a patient has morning stiffness and fatigue in addition to joint swelling and pain. If morning stiffness and fatigue are present for 9 months, and joint pain and swelling are present for 3 weeks, should the patient be considered in or out of the treatment window? van Nies’ data suggest that patients should be placed in the treatment window, and future studies should address the length of the treatment window for different onset types. many patients who are positive for ACPA and have joint pain develop RA. van Nies et al. show that if the duration of joint pain is greater than 6 months before the onset of RA The data from van Nies et al. show that if the duration of arthralgia is longer than 6 months before the onset of RA, patients lose their “window of opportunity” even if treatment is started at the onset of joint swelling. In the future, systematic use of imaging studies such as MRI and ultrasound at different stages of the disease is needed to better understand the relationship between the duration of symptoms, the true extent of synovitis, and the response to treatment.