Background and aim: The prevalence of tobacco smoking among individuals receiving treatment for substance use disorder (SUD) remains high. Respiratory disease and other harms are of prime concern to health policy makers, given the contributory role played by tobacco smoking in the excess rates of premature mortality seen in individuals with SUD. The aim was to use SUD treatment data to investigate tobacco smoking prevalence, among subgroups of adults over the course of treatment. Methods: We used the English National Drug Treatment Monitoring System (NDTMS) to examine number of days tobacco had been smoked in the previous month in adults receiving SUD treatment (N=106,472, median length of treatment 157 days). Results: At baseline (treatment start), 48.7% reported smoking tobacco; the highest rate was observed in opiate users (61%). Overall, the level of smoking at the latest assessment was 48.5%. Reductions (of between 5% and 7%) were observed among those who finished treatment but only within the final stages of treatment. A 5% increase in smoking was observed in those still in treatment within the study timeframe. Conclusions: This study identifies the potential for a greater emphasis on reducing tobacco consumption within SUD treatment, for example, by offering all smokers within SUD treatment smoking cessation support as part of their SUD treatment programme.