Our investigation of the occurrence of the enzymes phosphoglucomutase (PGM), glutamate-pyruvate-transaminase (GPT), adenylatkinase (AK), adenosine-desaminase (ADA), and 6-phophogluconate-dehydrogenase (6-PGD) produced the following results: The phosphoglucomutase type was demonstrated in the most sperm samples and seminal stains in accordance with the corresponding blood type. This enzyme is rather stable and could still be demonstrated well in 1-month old stains. The glutamate-pyruvate-transaminase can only seldom be determined in semen and seminal stains. We only found the GPT 1 type, which is known to have usually the strongest activity. The adenylatekinase was demonstrable in the most fresh ejaculates (not older than 24 h) and in about half the seminal stains (not older than 7 days)--The AK--2-band gets weak with increasing lay days, which may lead to incorrect determinations. The adenosine-desaminase could not be determined in sperm. On the contrary, 6-phosphogluconate-dehydrogenase could be demonstrated in fresh semen samples and also partly in seminal stains up to 7 days. The demonstration of the enzymes did not depend in any system on the secretor type.