Background: Health behaviour changes may improve the quality of life and survival among cancer survivors. We prospectively examined changes in health behaviour among and between men with prostate cancer (PC), men with cancers other than PC and cancer-free men. Methods: We analysed data for 20 914 men (50-65 years), 426 with cancer, and 20 488 persons who were cancer-free between baseline (1993-1997) and follow-up (2000-2002) in multiple linear regression models to determine differences in changes in body mass index (BMI) and in alcohol and tobacco consumption.ResultsBody mass index and tobacco and alcohol consumption decreased significantly (P<0.001) between baseline and follow-up among both men with cancer and cancer-free men. Men with cancers other than PC significantly decreased their BMI (Β058; 95% confidence interval (CI): 0.77, 0.40) and tobacco consumption (Β=-1.36; 95% CI:-2.22, 0.49) compared with cancer-free men and were significantly more likely to quit smoking and lose weight. Conclusion: Men with cancers other than PC decreased their tobacco consumption and BMI significantly more than cancer-free men. Men with cancer do change their health behaviour; clinicians should take this into account in planning follow-up care for cancer survivors.