Objective. - In a modified case-control association study we tested the assumption that two polymorphisms (A118G in exon 1 and IVS2+31 in intron 2) of the human ��-opioid receptor gene (OPRM1) confer susceptibility to opioid dependence. Methods. - In contrast to classical case-control studies both groups, opioid dependent cases and non-opioid dependent controls were recruited from individuals who have had access to drugs including opioids and who had been sentenced for violation of the "Dangerous Drugs Act" in Germany. Results. - For the two allelic variants of OPRM1 under study we did not find evidence for association with opioid dependence. Conclusions. - Despite absence of association we think that this recruitment approach introduced here, is useful since it putatively offers a more adequate matching for case-control association studies of opioid dependent individuals. �� 2003 ��ditions scientifiques et m��dicales Elsevier SAS. All rights reserved.