Results of the study of incidence of chlamydia trachomatis infection in patients with Reiters syndrome are presented. Chlamydia trachomatic was isolated from the uretral smear in 12 (34.28%) of 35 patients with Reiter's syndrome. In the group of patients with other rheumatologic diseases Chlamydia trachomatis was isolated in 2 (5.13%) of 39 patients. In all patients with negative isolation, infection was confirmed serologically also and in some patients with negative isolation it was also proved.