Mycotoxins are toxic secondary metabolites of moulds. Mycotoxins have adverse effects on crops, domestic animals and humans, causing many diseases. However, some type of moulds and their secondary metabolites are not toxic. Pseurotin A and Pseurotin D, secondary metabolites first isolated from the cultures of Pseudeurotium ovalis STOLK, have different structures and diverse bioactivity. Because of these characteristics an interest in these compounds has significantly increased. The main goal of the present research was to investigate the effects of natural pseurotins on human lymphoma cell line. For this purpose, MEC-1 cell line, derived from human chronic B cell leukemia, was treated with different concentrations of PsA and PsD. To investigate the effects on viability and cytotoxicity of lymphoma cells, both PsA and PsD were used. In order to investigate the effects on cell cycle and cell death (apoptosis) of lymphoma cells, only PsD was used. The results show that none of the concentrations of PsA significantly affected cell proliferation, cellular metabolism and cytotoxicity. Contrary to that, PsD affected the tested cells in concentrations of 20 μM, 25 μM and 50 μM. After 24 h, PsD significantly inhibited the cell cycle and decreased expression of cyclins, but did not affect apoptosis of cell line in used concentrations (1M, 5 M, 10 M and 25 M) after 24, 48 and 72 h.