From January 1, 1990 to December 31, 1994, DBCG conducted a randomised trial in 1 615 postmenopausal women with operable, high-risk, receptor-positive or -unknown breast cancer. The patients were after surgery randomised to Tamoxifen for 1 year (TAM1), Tamoxifen for 2 years (TAM 2) or Tamoxifen for 6 months followed by megestrol acetate for 6 months (TAM/MA). When the preplanned sample size of 1 500 patients was reached it was decided to continue randomisation to TAM1 or TAM2 and the study was finally closed December 31, 1996. With a median follow-up of more than 10 years, there was no difference in disease-free survival (DFS) or overall survival (OS) among the three treatment arms. Similar results were obtained in the original and extended comparisons of Tamoxifen for 1 versus 2 years. A multivariate analysis in the per-protocol treated patients did not show significant differences in hazard ratios for DFS or OS among the three arms. Side-effects were rare but more common in the TAM2 and TAM/MA arms.