BCF1 (bioconcentration factor after the one day of exposition) value of BaP [benzo(a)pyrene] in strain A-8, Chlorella vulgaris Beijerinck 1890 (Chlorella BB) was studied. The algae were cultured in a modified Ku¨hl-Lorentzen liquid medium at room temperature, under continuous illumination and stirring for 24 hours. The final average value of BCF1 equalled 2100 ± 140 for BaP initial concentrations in the range from 0.005 to 0.5 mg/cm3 in the culture medium. Statistical analysis of the results revealed independence of the bioconcentration factor from initial concentration of BaP. The BaP amount determined in the samples after the experiment differed markedly from the initial amount introduced to the mediums.