A hospitalization is a time when perceived vulnerability to dangers from smoking and quitting motivation may be at their peak. Aim was to determine whether a smoking cessation intervention of moderate intensity would increase the smoking cessation rate in hospitalized smokers. Design was randomized trial, conducted in a university-affiliated cardio-pulmonary tertiary care center. Participants were hospitalized smokers aged < or =70 years. Intervention was a smoking cessation intervention consisting of education and psychological support, with or without pharmacological therapy, associated with follow-up phone calls. Patients assigned to the control group received usual care. Measurement was point prevalence cessation rate at 1-year follow-up. A total of 468 patients were screened; 196 were randomized. Although the smoking cessation rates at 12-month follow-up were higher than expected, we found no significant difference between the study groups (intervention: 30.3%; control: 27.8%). Similar results were obtained in patients whose smoking status was validated by urinary cotinine assay. Length of stay and dependence to nicotine were the only significant predictors of smoking cessation. A smoking cessation intervention of moderate intensity delivered in a tertiary cardio-pulmonary center did not increase the smoking cessation rate at 1-year follow-up. The results of this trial should not divert those who deliver care to inpatients from delivering a brief smoking cessation intervention.