This randomized, double blind, placebo controlled, phase I clinical trial assessed the safety and immunogenicity of a therapeutic cocaine vaccine TA-CD in 34 former cocaine abusers: 8 at 13 microg active vaccine, 10 at 82 microg and 10 at 709 microg, with two additional subjects getting placebo in each cohort. All got intra-muscular injections at 0-2 months and were monitored for safety and antibody production for 3 months. Of the 34 subjects 27 completed the full course of three injections, of these, only 24 returned for the final scheduled visit at day 84. The vaccine was well-tolerated and had no serious drug-related adverse events, although three subjects at the highest dose experienced brief post injection twitching. Fifteen subjects on TA-CD therapeutic vaccine were followed for 1 year. Antibody levels were correlated with vaccine dose and number of injections. Anti-cocaine antibodies were detected after the second injection, peaked at 3 months and declined to baseline by 1 year. Thus, the therapeutic vaccine was well tolerated with dose related increases in antibody levels, and a high proportion of patients recruited into the study were retained.