A sample of 140 Chuetas (descendants of Majorcan Jews) were typed for the GC, A2HS, ORM, ITI and HP serum proteins. Studies on ORM and ITI markers have not yet been reported in other Jewish populations. The allele frequencies obtained were: GC*1 = 0.610; A2HS*1 = 0.787; ORM*F1 = 0.339; ORM*S = 0.497; ITI*1 = 0.581; ITI*2 = 0.414; HP*2FS = 0.625; HP*1S = 0.230; HP*1F = 0.135. Some rare variants were found in polymorphic frequencies (ORM*S1 = 0.043; ORMS*S2 = 0.096; A2HS*10 = 0.015). These results have been compared with those found in other Jewish and non-Jewish European populations. The relatively high frequency of the HP*2FS allele and the presence of ORM*S1 and ORM*S2 variants in Chuetas show the Jewish origin of this population. The frequencies of GC and A2HS in Chuetas are similar to those found in other surrounding non-Jewish populations. ITI results are similar to those found in the two European populations studied. HP frequencies suggest a Spanish admixture.