Objective. To determine the prevalence of Chlamydia trachomatis infection among registered prostitutes of Durango City and to establish whether there is a correlation between epidemiological factors and infection. Material and methods. Two-hundred-and-forty-seven registered prostitutes of Durango city were studied. Endocervical samples and epidemiological data were obtained. C. trachomatis antigen was detected with the Chlamydiazyme test (Abbott Laboratories, USA.) Results. Forty-one (16.6%) out of 247 prostitutes were positive to C. trachomatis. Thirty-seven out of the 41 positive women had had sexual activity on several States of Mexico (95.1%), as compared to only 109 out of 206 negative women (53.0%) (p<.0001). Prostitutes positive to C. trachomatis (39/41, 95.1%) were more likely to belong to low socioeconomic level than negatives (171/206, 83%) (p=0.05). Conclusions. The prevalence of C. trachomatis infection was 16.6%. C. trachomatis infection was associated with sexual activity in multiple States of Mexico, and had a tendency to be associated with low socioeconomic level.