Abstract: OBJECTIVES. Serial, cross-sectional trends in injecting risk behavior were studied among drug users from 1986 to 1992. METHODS. From a cohort study in Amsterdam, 616 intake visits of drug users who had injected in the 6 months preceding intake were selected. RESULTS. The proportion of drug users who reported borrowing and lending used injection equipment and reusing needles/syringes (in the previous 6 months), continuously declined from 51% to 20%, from 46% to 10% and from 63% to 39%, respectively. In multivariate analysis, it appeared unlikely that a selective recruitment of participants over time was responsible for these trends. Participants, recruited later in time, had been previously tested for human immunodeficiency virus (HIV) more often, had received daily methadone less often, and had obtained a higher proportion of new needles via exchange programs. Indications were found that (1) voluntary HIV testing and counseling leads to less borrowing, lending, and reusing equipment; and (2) obtaining needles via exchange programs leads to less reusing needles/syringes. It appeared that nonattenders of methadone and exchange programs have reduced borrowing and lending to the same extent as attenders. CONCLUSIONS. Methodologically, evaluating specific measures is difficult. However, the combination of various preventive measures in Amsterdam is likely to be responsible for the observed decrease in injecting risk behavior.