['Studies assessing the efficacy of azathioprine (AZA) in steroid-dependent ulcerative colitis (UC) are scarce. The aim of this study was to assess the long-term efficacy and safety of AZA in patients with steroid-dependent UC, as well as factors associated with sustained response.', 'In this prospective observational study 46 adult subjects with steroid-dependent UC were included for AZA therapy during a 12-month period. AZA dosage was adjusted according to clinical response and occurrence of adverse events. Steroid therapy was tapered according to protocol. The primary endpoint was the rate of steroid-free remission to AZA at the end of 12 months. Secondary endpoints included clinical relapse, cumulative steroid dose and safety of treatment.', 'On an intention-to-treat basis, the proportion of patients remaining in steroid-free remission at the end of 12 months was 0.54. The median time until complete steroid withdrawal was 5 months. A significant decrease in the relapse rate and in requirement for steroids were observed during 12 months on AZA compared with the prior year (P=0.000). Demographic, dose of AZA, steroid use, and disease-related data did not correlate with remission. Only disease duration <24 months was associated to steroid-free remission (P=0.03, OR 3.60 95% CI 1.95-9.74). Serious adverse events related to AZA were uncommon.'] Is early onset steroid-dependent ulcerative colitis a predictor of azathioprine response : a longitudinal 12-month follow-up study?