A cohort study of 174 flat-coated retrievers was undertaken to establish the importance of cancer in flat coat mortality in terms of the prevalence of neoplasia in the breed and also the relative effect of cancer on lifespan in relation to other forms of mortality. Dogs aged 2-7 years were recruited in 1996 and followed until 2007. An annual health census was used to collect the data. Two dogs were lost to follow-up and 72 dogs (42%) died from confirmed neoplasia. Twenty dogs (11.6%) died of unconfirmed tumours and 61 (35%) died from non-neoplastic conditions. The cause of death was unknown for 19 dogs. Soft tissue sarcoma (especially histiocytic sarcoma) was the predominant cancer type, affecting 32 dogs (44% of neoplasms). Six dogs died with malignant melanoma and three with lymphoma. Median age at death was 9 years for dogs with tumours (eight for sarcoma patients) and 12 years for non-neoplastic fatalities. The results confirm that soft tissue sarcoma, particularly histiocytic sarcoma, is a major cause of mortality in this breed.