Objective: To evaluate the effectiveness of inpatient brief counselling by a smoking cessation nurse compared to usual care (no advice). Methods: The subjects (n = 381, 245 men and 136 women) studied were in-patients, in four Flemish University Hospitals, who were daily smokers. Patients were randomised between 2005 and June 2006. Patients were allocated to an experimental group (EG) or to a control group (CG). Allocation and smoking cessation interventions of patients were stage-matched according to their stage of change as defined by Prochaska and Diclemente. Smoking cessation advice was administered by a qualified smoking cessation nurse. Results: The six-month self-reported continuous abstinence in the EG in 28/178 patients (15.7%) compared to the CG where 14/180 patients were abstinent (7.7%) was significantly better. The effect was most pronounced in the subgroup over 40 years old in the preparation and action stage. In this cohort in the EG, 44% of patients were abstinent at six months compared to 18%in the CG. All patients tended to smoke less after a hospitalisation. Conclusion: The intervention by a smoking cessation nurse during hospitalisation seems effective and is most rewarding in the smokers > 40 years old, and who were well motivated to stop.