Aims. To evaluate the effectiveness of a motivational intervention to reduce attrition from a waiting list for substance abusers seeking publicly funded treatment. Design. Randomized clinical trial comparing an "attrition prevention" condition to standard care while awaiting treatment admission. Setting. A centralized substance abuse assessment and referral center in Seattle, Washington. Participants. Substance abusers (n = 654) eligible for publicly funded drug abuse treatment. Measurements. Alcohol and drug use, substance-related negative consequences, areas in need of help, perceived need for help, emotional status, readiness to change, reasons for seeking and perceived barriers to entering treatment. Findings. Overall, approximately 70% of clients entered treatment, and of these approximately 70% completed their assigned treatment. Those who entered treatment showed significant reductions in substance use and improved psychosocial function at a short-term 3-month follow-up. However, the attrition prevention intervention had no differential effect on treatment entry, completion or outcome compared to the standard waiting list. Further, there were no differences across therapists on these outcome measures. Conclusions. A motivational attrition prevention intervention did not enhance treatment entry, completion or outcome among treatment-seeking substance abusers. It is suggested that alternative strategies, such as contingency management and case management, may help facilitate treatment entry for individuals seeking publicly funded treatment. (Author' s abstract)