Sulphoglycoprotein antigens of the foetal alimentary canal have been studied by the immunofluorescence technique, and the presence of sulphomucins demonstrated histochemically from adj,cent sections. The materia[studied consistedof 39 foetuses of between 6 and 16 weeks of gestation. A suppIem~nta~y autopsy series of newborns was studied by the same techniques. The three sulphoglycoprotein antigens found earlier in normal and pathological adult gastric mucosa appeared between 7 and 8 weeks of gestation and all were present in the foetal alimentary epithelium. The typical location of these antigens showed characteristics either of the normal adult distribution or of the distribution found in pathological conditions in the gastric epithelium. The ca-antigen (cancer antigen) present in cancerous gastric epithelium in adults has now been tentatively named the foetal sulphoglycoprotein antigen ( F S A ) . A comparison is made between the distribution of the sulphoglycoprotein antigens detected by the immunofluorescence technique and that of the sulphomucins seen by histochemical methods. It is suggested that these antigens are mainly situated in sulphated molecules.