A sample of 2143 individuals from Mallorca, coming from six geographic regions of this island: "Es Raiguer", "La Muntanya", "Es Plà", "Mijgorn", "Llevant" and "Palma", as well as 390 individuals from Eivissa island have been studied for the following six red cell enzyme systems: Esterase-D (ESD), acid phosphatase-1 (ACP1), glyoxalase-I (GLO1) 6-phosphogluconate dehydrogenase (PGD), phosphoglucomutase-1 (PGM1) and adenylate-kinase (AK1). The data were processed by means of multivariate statistical procedures: principal components, factorial correspondence and cluster analyses. The results indicate that ACP1 and ESD were the most suitable systems for the characterization of these caucasian populations, while GLO1 was important when different ethnic groups were included in the analyses. The Balearic gene frequencies fell within the European standard. Slight genetic distances were detected among the different Balearic populations, notably with the exception of the high differentiation of "La Muntanya".