[reaction: see text] Novel inhibitors of human digestive lipases, aldehyde dialkyl and alkyl-acyl glycerol analogues, were developed. The inhibitors were prepared starting from 3-(benzyloxy)-1,2-propanediol. The inhibition of human pancreatic and gastric lipases by the aldehyde derivatives was studied using the monolayer technique. (1R)-1-[(Dodecyloxy)methyl]-4-oxobutyl decanoate caused a 50% decrease in HPL and HGL activities at 0.100 and 0.053 molar fractions, respectively.