Human biomonitoring of the lipid peroxidation DNA modification 1,N6-ethenodeoxyadenosine (epsilondA) excreted into urine is thought to be a potential marker for oxidative stress-related DNA damage and human cancer. We have tested this hypothesis in a prospective, nested case-control study. During the years 1984-1989, 24-h urines were collected from 1956 men in the Kuopio Ischaemic Heart Disease (KIHD) Risk Factor Study. epsilondA concentrations were measured by LC-MS/MS in 24-h urine samples from 47 men with cancer diagnosed at follow up until 2001 and from 31 cancer free smoking-matched control subjects. Odds ratio for having higher than control median epsilon dA excretion rate and cancer, estimated by binary logistic regression, was 0.73 (95% CI 0.29-1.80, p = 0.49). In this study, the urinary excretion of epsilondA provides no additional prediction of cancer development in males after controlling for smoking.