Provider-initiated HIV testing and counseling (PITC) has rapidly expanded in many countries including Uganda. However, because it provides HIV prevention information without individualized risk assessment and risk reduction counseling it may create missed opportunities for effective HIV prevention counseling. Our objective was to assess the effect of a brief motivational interviewing-based intervention during outpatient PITC in rural Uganda compared to Uganda's standard-of-care PITC at reducing HIV transmission-relevant sexual risk behavior. We enrolled 333 (160 control, 173 intervention) participants in a historical control trial to test the intervention vs. standard-of-care. Participants received PITC and standard-of-care or the intervention counseling and we assessed sexual risk behavior at baseline and 3 and 6 months follow-up. The intervention condition showed 1.5-2.4 times greater decreases in high risk sexual behavior over time compared to standard-of-care (p = 0.015 and p = 0.004). These data suggest that motivational interviewing based counseling during PITC may be a promising intervention to reduce high-risk sexual behavior and potentially reduce risk of HIV infection.