Cultures of freshwater microalgae (Chlorella vulgaris) (2 L) were periodically inoculated (30-50 cm(3)) and every 4 days supplied with nutrient and vitamin solns. (1-2 cm(3) and 1 cm(3), resp.). The process was conducted at 28 degrees C and pH 7-9 as well as under stirring (260 rpm) and light exposure (780-800 lux). The highest daily mass gain exceeded 200 mg/dm(3) for the sample with the highest content of inoculum. The final content of dry algae biomass was almost 6 times higher than the initial value.