The perianal folds are very itchy every night, considering the perianal eczema, pinworms and anal fistula and other causes. 1. Perianal eczema: patients due to hemorrhoids, anal fissure and other chronic inflammatory stimuli or anal contact with alcohol, strong acid and other stimuli and induced eczema. The anal area often appear flushing, papules, blisters, vesicles and scabs and other manifestations, mostly accompanied by intense itching, so it can be seen in the folds of the perianal area is very itchy every night. 2. Pinworm disease: patients often due to their own or foreign body pinworm infection and morbidity, preferably in children. Patients can appear typical perianal or perineal itching, mostly due to the toxic substances produced by pinworms and mechanical stimulation, more pronounced at night, affecting sleep, so it can be seen in the perianal folds itchy every night. 3. anal fistula: patients due to perianal abscess, perineal surgery, anal fissure recurrent infection and so on and lead to anorectal fistula. Because of the fistula opening around the anus outside, the intestinal cavity oozing mucus or feces through the fistula stimulation around the anus and produce inflammation, which in turn causes itching symptoms, so it can be seen in the perianal folds itchy every night. Once you find the perianal folds itchy every night, it is recommended to consult the hospital as soon as possible, the relevant examination, a clear diagnosis.