The purpose of this study was to compare substance involvement among psychiatrically hospitalized adolescent smokers who had received motivational interviewing (MI) versus brief advice (BA) for smoking cessation. One hundred and ninety-one (191) adolescent smokers (62.3% female; 15.4 years of age) were randomly assigned to MI (n=116) or BA (n=75). All patients were assessed at baseline, immediately after hospitalization, and at 1-, 3-, 6-, 9-, and 12-month follow-ups. Rates of substance use in the MI condition during follow-up increased from a low of 8.2% (SD=18.5) to a high of 15.4% (SD=30.0) substance use days, whereas in BA, substance use days increased from a low of 8.4% (SD=20.8) to a high of 21.4% (SD=35.2). The results of this study suggest that MI, relative to BA, for smoking cessation was associated with better substance use outcomes during the first 6 months following psychiatric hospitalization among adolescents. This finding is consistent with previous studies that have shown that smoking cessation does not have a detrimental effect on substance abuse treatment outcomes among youth.