To determine whether the simultaneous, partial repeal of needle prescription and drug paraphernalia laws in Connecticut affected purchasing and usage of needles and syringes (syringes) by injecting-drug users (IDUs) and risk of needlestick injuries to police officers, we conducted two serial cross-sectional surveys with IDUs recruited in drug treatment centers, correctional facilities, and health department settings. Reports of needlestick injuries among Hartford police officers were reviewed before and after the new laws. Among IDUs who reported ever sharing a syringe, syringe-sharing decreased after the new laws (52% before vs. 31% after; p = 0.02). Fewer IDUs reported purchasing syringes on the street after the new laws (74% before vs. 28% after; p < 0.0001). More IDUs reported purchasing syringes from a pharmacy after the new laws (19% before vs. 78% after; p < 0.0001). Eight to eleven months after the new laws were enacted, over two thirds (91 of 134) of active IDUs interviewed were aware of both new laws. Needlestick injury rates among Hartford police officers were lower after the new laws (six injuries in 1,007 drug-related arrests for 6-month period before new laws vs. two in 1,032 arrests for 6-month period after new laws). The changes in Connecticut laws were associated with decreases in self-reported syringe-sharing and increases in purchasing by IDUs of sterile syringes from reliable sources, suggesting that the simultaneous repeal of both prescription and paraphernalia laws is an important HIV prevention strategy.