Strains of P.a. were isolated from seborrheic filaments from 11 persons and investigated according to their production of porphyrins. After growing the organisms during a 5 resp. 10 days cultivation period on solid as well as in liquid culture medium the quantity and quality of the bacterial porphyrins were determined. There existed intense variations in quantity not only when the special strains were compared with each other but also when the same strains were treated with different preparations. The porphyrin-spectrum, as demonstrated by thin-layer-chromatography, showed porphyrins with 2--8 carboxyclic groups, the coproporphyrin standing out in most cases as the most intense band.