Objectives: To describe trends in STD visits to physicians in private practice in Peru over a 15 year period and in the patterns of treatments used for STD. Methods: IMS Health conducts for pharmaceutical marketing purposes surveys of a random cluster sample of 1.63% of practising physicians in Peru, stratified by region and specialty. Physicians record details of diagnoses and treatments for all patients seen during a 7 day period every 6 months. Data collected on selected STD syndromes were retrospectively reviewed over a 15 year period. Results: The number of first visits for pelvic inflammatory disease (PID) and trichomoniasis, and total visits for genital herpes increased from 1983-5 to 1996-7; while first visits for gonorrhoea and total visits for syphilis have changed little in recent years. Treatment for gonorrhoea usually involved the use of spectinomycin or an aminoglycoside only. Treatments offered for PID were remarkably inadequate and for trichomoniasis often involved products not known to be effective for trichomoniasis or other causes of vaginal discharge. Conclusions: This form of active surveillance provides information potentially useful to guide policies for prevention and management of STDs and HIV infections in developing countries.