Serum haptoglobin, transferrin and albumin were studied electrophoretically in 50 patients with carcinoma of breast and in 50 normal healthy women. Results on haptoglobin show a preponderance of products of gene Hp1 (0.26) in patients as compared to controls (0.14). No variation was observed at the transferrin locus in either sample. The most notable finding was the detection of four cases of alloalbuminaemia (8%) in breast cancer Patients. The high incidence of alloalbuminaemia prompted us to extend our observations further. For this purpose sera from 41 patients was collected. One more case of alloalbuminaemia of the fast type was detected. However, in contrast to our first series of patients, quite high incidence (12.2%) of transferrin variants was recorded in this sample. Family studies were conducted on all the patients with protein anomalies.