From a random northern German sample, gene frequencies of five red cell enzyme polymorphisms are calculated. For acid phosphatase (n = 7,059) the gene frequencies are estimated to be: pa = 0.353, pb = 0.582, pc = 0.065; for phosphoglucomutase (n = 4,403): PGM21 = 0.217, PGM11 = 0.783; for adenylate kinase (n = 2,370): AK1 = 0.966, AK2 = 0.034; for adenosine deaminase (n = 1,070): ADA1 = 0.945, ADA2 = 0.055, and for 6-phosρho-gluconate dehydrogenase (n = 1,162): PGDA = 0.9798, PGDB = 0.0202. A good agreement between observed and expected numbers has been found except in the acid phosphatase system. Comparative population genetic studies reveal certain north to south differences for three polymorphisms. The frequencies of the genes pb, pc, PGM21 and ADA2 seem to be significantly higher in southern European populations than in northern and middle Europeans which seem to be rather similar