Histochemical features of mucin were studied in a group of advanced cancers of the stomach. Study failed to find any essential difference in mucosubstances composition between diffuse type and intestinal type carcinomas. Proportion of single sulphated, non-sulphated and neutral components was always changing even in different parts of one tumour. An acid mucus with extracellular and intracellular admixture of O-acylsialomucin prevailed in 4 mucinous carcinomas similarly as in colorectal mucinous carcinomas. The study showed that single histologic types of carcinoma in different abdominal parts of digestive tract could not match in frequency but shared features of secretion without making any difference in localization. Occurrence of mixed tumours gives evidence of derivation of carcinomas from a common stem cell with various differentiang abilities.