Some patients often ask if they have rheumatoid arthritis when their rheumatoid factor (RF) is positive or slightly elevated, and they are scared to death. Is the rheumatoid factor (RF) the only indicator to diagnose rheumatic diseases? The answer is no. Rheumatoid factor (RF) is certainly not the only indicator for the diagnosis of rheumatic diseases. The reasons are as follows: 1. Rheumatoid factor (RF) is one of the indicators for the diagnosis of rheumatoid arthritis. Only 70% of rheumatoid arthritis RF positive. Other diseases and some healthy people can also be positive for RF. In normal people also have a positive rate of 5%, and its positive rate increases with age. 2, RF positive, can be rheumatoid arthritis, but systemic lupus erythematosus, dry syndrome, etc. can also appear positive. Non-rheumatic diseases, such as hepatitis, infection, infective endocarditis can also appear RF positive. However, if rheumatoid arthritis has been diagnosed, the higher the RF titer, it suggests that the patient’s arthritis is more serious and more likely to lead to joint destruction. 3, RF negative, does not necessarily exclude rheumatic disease. There are still 20% to 30% of rheumatoid arthritis patients can appear RF negative. RF is not a specific indicator of RA. RF (-) does not exclude RA, RF (+) is not certain to be RA .