BACKGROUND: This study evaluated the effectiveness of three smoking cessation interventions for this population: (1) modified usual care (UC); (2) brief advice (A); and (3) brief advice plus more extended counseling during and after hospitalization (A + C). METHODS: Smokers (2,095) who were in-patients in four hospitals were randomly assigned to condition. Smoking status was ascertained via phone interview 7 days and 12 months post-discharge. At 12 months, reports of abstinence were validated by analysis of saliva cotinine. Intent to treat analyses were performed. RESULTS: At 7-day follow-up, 24.2% of participants reported abstinence in the previous 7 days. There were no differences between conditions. At 12-month follow-up, self-reported abstinence was significantly higher in the A + C condition (UC (15.0%) vs. A (15.2%) vs. A + C (19.8%)). There was no significant difference among conditions in cotinine-validated abstinence, however (UC (8.8%) vs. A (10.0%) vs. A + C (9.9%)). CONCLUSIONS: These interventions for hospital in-patients did not increase abstinence rates. Features of the study that might have contributed to this finding were the inclusiveness of the participation criteria, the fact that pharmacological aids were not provided, and a stage-matching approach that resulted in less intensive counseling for participants unwilling to set a quit date.