The biological availability of artificial beta-carotene as a water-soluble versus oily formulation based on cyclodextrin (Cyclocar tablets) was studied on volunteers given a single dose of 25 mg. The concentrations of beta-carotene and major carotenoids were measured in the blood serum during the experiment by high performance liquid chromatography. The maximum content of beta-carotene in the serum was attained 24-30 and 30-48 hrs after oily formulations and Cyclocar and were 48.0 +/- 7.7 and 28.1 +/- 3.6 mg/dl, respectively. The rate of beta-carotene utilization from Cyclocar was 2.2 times less than that from the oil paste. Besides, beta-carotene absorbed from these oily drugs retained in the blood serum for longer period than that form Cyclocar.