The aim was to estimate the cancer mortality explained by tobacco smoking and alcohol risk drinking. The methods included (1) smoking rates from the largest population survey and alcohol drinking data from the German National Health Survey, and (2) vital statistics from Germany. The tobacco- and alcohol-related data were analysed using formulas for the estimation of attributable fractions. The results show that 19.7% of all malignant neoplasm deaths are explained by tobacco smoking alone, a further 0.2% by alcohol consumption alone and a further 5.6% by tobacco smoking and alcohol drinking. It is concluded that this overlap in the two substance use behaviours has to be taken into account when considering attributable mortality data.