Some investigations on the influence of molecular structure on olfactory quality will be discussed. The influence of molecular structure on the olfactory quality of compounds with a fruity odor characteristic will be discussed in more detail. More than 100 esters with the following profile elements were studied : alphatic, aromatic, homocyclic. We have found in a quantitative approach to structure-odor relationship that : 1) the steric parameters; i.e., profile elements : aliphatic, arylepoxide and homocyclic, have significant influence; 2) the physicochemical parameters, molecular weight and partition coefficient, are not significant over the whole group; however, they do show some significance within subgroups.