Objective: The aim of this study was to examine whether brief training of human immunodeficiency virus (HIV) medical providers increased the frequency with which they routinely delivered prevention counselling to patients, and whether patient characteristics were associated with receipt of that counselling. Design: Longitudinal. Setting: Seven HIV clinics in the United States. Method: Medical providers received training to deliver counselling to their HIV-positive patients. The evaluation was conducted with a longitudinal cohort ("N" = 729) of patients at baseline (before providers received training) and at six and 12 months after the intervention was initiated. Participants reported on receipt of routine counselling (at more than half of their primary care visits) about safer sex, disclosing HIV infection to sex partners, and alcohol/drug use. Logistic regression and generalized estimating equations (GEE) methods assessed changes in receipt of counselling over time. Results: The percentage of participants reporting routine safer-sex counselling increased significantly across time (b = 0.12, standard error [SE] = 0.04; "p" = 0.004), as did receipt of routine counselling about disclosing their HIV infection to sex partners (b = 0.21, SE = 0.05; "p" less than 0.001). The trend was not significant for counselling about alcohol or drug use. Sub-group analysis indicated that the upward trend in routine safer-sex counselling was significant for men who have sex with men (MSM), for participants who had more than one sexual partner in the past three months, and for those who had a CD4 count of greater than 500cells/mm[superscript 3]. Conclusion: Brief training increased the frequency with which HIV medical providers routinely delivered prevention counselling to their patients at risk of transmitting HIV to others. (Contains 4 tables.)