In a retrospective review of 73 patients with in situ breast carcinoma seen in the Combined Breast Clinic at the Royal Marsden and St. George's Hospitals between 1969 and 1988, 20 (27%) were found to have in situ lobular and 53 (73%) in situ intraduct carcinoma. Of 19 patients with in situ lobular carcinoma treated by breast conserving surgery alone there were three (16%) recurrences of in situ lobular carcinoma and one (5%) of infiltrating carcinoma after a mean follow-up period of 65.8 months. Of 53 patients with in situ intraduct carcinoma, 37 were treated by breast conserving surgery alone and in this group there were 14 (38%) recurrences, of which seven (19%) were in situ intraduct and seven (19%) were infiltrating carcinoma, after a mean follow-up of 96.5 months. Following successful salvage there were no breast cancer related deaths in either group.