Abstract 1. 1. Further studies have been carried out on the specificity of laminaribiose- and β-1,3-oligoglucan phosphorylase. Both enzymes, present in extracts of Euglena gracilis, could be separated either by calcium phosphate gel or by DEAE-cellulose column chromatography. 2. 2.|From the data presented it can be concluded that the two enzymes catalyze the same reaction but with different quantitative specificity. The β-1,3-oligoglucan phosphorylase was found to phosphorolyze laminaritriose and higher homologues at a greater rate than laminaribiose while the opposite behavior was observed with laminaribiose phosphorylase. 3. 3.|Another, and probably more striking, difference between the two enzymes was the fact that aged preparations of β-1,3-oligoglucan phosphorylase showed an absolute requirement of sulfhydryl donors while laminaribiose phosphorylase was only slightly activated. 4. 4.|The possibility that the qualitative similarity might be due to a cross-contamination of the enzymatic fractions was discarded by competition experiments between substrates and by the elution pattern of the DEAE-cellulose chromatography.