The aim of this study was to evaluate whether patients with salivary gland tumours are at increased risk of developing breast cancer. A retrospective cohort study was performed. Female patients (n = 439) with a salivary gland tumour (major and minor) were included. The diagnosis was confirmed histologically. The median follow-up was 5.4 years. Fifteen patients out of 439 with a salivary gland tumour subsequently developed breast cancer, with a mean time interval of 64 months. On the basis of incidence rates in the general population 5.93 breast cancers would be expected. The standardised incidence ratio (SIR) was 2.5 (95% confidence interval: 1.4-4.2; P = 0.003). Increased SIRs were also observed for other solid malignancies, but the numbers were small (n < 5). It is concluded that female patients with a salivary gland tumour have a 2.5 times increased risk of developing breast cancer. Breast screening of these patients is therefore recommended.