The objective of the study was to evaluate the prevalence of Chlamydia trachomatis infection and the participation, among partners of asymptomatic cases in general practice. Index cases were requested to invite partners for testing by mailed urine samples. One or more partners of 62% of the index cases participated, and the prevalence of infection among partners was 48%. A steady relationship was a determinant of both participation and prevalence. In conclusion, the mailing strategy is an effective strategy for partner notification. A high prevalence wasfound among partners.