OBJECTIVE: To evaluate the association between smoking habits and outcome of patients with superficial bladder cancer. METHODS: A retrospective study was performed evaluating 99 patients (67.0 ± 13.2 years, ranging from 31.4-93.4 years, 72.7% males and 27.3% females) treated at our institution with non muscle-invasive bladder cancer, between 1994 and 2000, with a mean follow-up of 49.3 months (range 4.0-177.9 months). Patients were divided according to smoking status, and the main measured outcome was progression to invasive disease. Additional cohort analysis was performed dividing patients according to previous tobacco exposure: smokers and non-smokers. Smokers were stratified into former smokers, early-quitters, late quitters and continued smokers. RESULTS: Smoking habit was significantly more common in males (p = 0.03). Cancer also occurred at an earlier age among smokers (70.8 versus 64.8 years, p = 0.030). Tobacco consumption was present in 62.7% of the patients with bladder cancer. There was a significant higher progression rate to muscle-invasive disease in patients that had more than 60 pack-years of exposure (52.9 versus 26.2%, p = 0.037). These patients had a mean progression time of 59.3 months, whereas patients who had smoked less than 60 pack-years progressed after a mean time of 131.8 months. CONCLUSIONS: A direct association between the amount of tobacco consumed and disease progression is observed in patients with bladder cancer, as suggested by the present study. Tobacco consumption has a direct association with progression of superficial bladder cancer to invasive disease and also shortens the period of time for muscle invasion. Larger and prospective studies are still necessary to bring further definitive conclusions about reproducibility of our data and to better understand how smoking cessation affects progression of superficial bladder cancer.