There is a national trend toward banning smoking in substance abuse facilities. Conventional wisdom considers it unreasonable to ask patients to stop smoking while withdrawing from other substances and is seen as reducing the chances of success. This project examined whether a smoking ban in an inpatient medical detoxification unit would deter patients. Admission logs were used to identify all patients admitted a year before and after the ban on tobacco. Results indicated stability in: the number of admissions; patient demographics; substance use pattern (alcohol abuse predominated); and tobacco use (80.2% vs. 84.0%). Average length of stay decreased a third of a day (P<.05), which did not appear to be due to discharges to other substance abuse units or leaving against medical advice, as these did not change significantly (P>.10). Thus, the ban did not appear to have any notable impact in deterring patients from seeking or staying in treatment.