The genetic polymorphism of four red cell enzymatic systems (ESD, ACP1, GLO1 and PGD) has been studied in the "Chueta" community (descendants of converted Jews from Majorca Island). The results have been compared with those of the population of Majorca that has no Jewish origin, and with other Jewish and non-Jewish Mediterranean populations. For these comparisons the following methods were used: chi 2 test, Wright's F, Nei's identities and distances and a dendrogram based on Nei's measures. The results obtained indicate that the Chueta community differs form the non-Chueta Majorcan population, although it resembles this non-Chueta population more closely than it does other Jewish ones.