The expression of Gal -(1,3)Gal ( Gal) on porcine islet cells remains controversial. Several groups have reported that porcine islet endocrine cells do not express Gal while we have shown in neonatal porcine islets (NPI) that cells do express this antigen. We hypothesize that endocrine cells expressing Gal on NPI are less mature cells that may have originated from ductal cells and that expression of this antigen disappears as they develop into fully mature cells. Thus, we further examined Gal expression on various porcine islet cell preparations and correlated this with the proportion of cytokeratin 7 (CK7)-positive ductal cells. In vitro and in vivo expression of Gal and CK7 was significantly (P<0·05) higher in less mature NPI cells compared with matured NPI and adult porcine islet cells while the reverse was observed in the proportion of cells. Moreover, a significantly higher proportion of CK7-positive cells was detected in the Gal-expressing population compared with non-expressing cells. In contrast, a higher proportion of cells was observed in the Galnegative population compared with the Gal-positive population. These data showed a reduced expression of Gal and CK7 as porcine islet cells mature into cells suggesting a possible role for Gal in the maturation of pancreatic endocrine cells.