The use of cytotoxic agents for the management of advanced breast cancer has shown a considerable increase over the past ten years. The great expectations that so many workers had in the early days of the new cytotoxic agents may have been disappointed but their use in producing worth-while regression or stasis of growth is acknowledged. A considerable amount of literature now exists reporting objective responses in advanced breast cancer produced by the drug cyclophosphamide which has now been in use since 1959. Over the past fiveyears we have treated 133 cases of advanced breast cancer which are suitable for assessment. This study is retrospective and is presented with all the requisite apologies and cautions. One hundred and two cases within this series were reported two years ago (Kunkler et al. 1967); the inclusion of a further 30 cases has allowed some improvement in our system of analysis and mainly substantiates our previous findings.