The aim of this study was to assess the influence of qualitative and quantitative base composition on pharmaceutical availability of metronidazole. Hydrogels contain water dispersion of 2% Carbopol 971P and various concentration of glycerol, polyethylene glycol and propylene glycol were preparated. Produced formulations were neutralized to the pH 6.0-6.5 with triethanolamine, and metronidazole in concentration 1% added. The test for pharmaceutical bioavailability was performed in vitro, the rate of diffusing therapeutic agent through a semipermable into acceptor fluid was tested. The quantity of metronidazole released at the same time intervals was tested by spectrophotometric method. Hydrogel consists of 99% water dispersion of Carbopol 971P and 1% glycerol characterized by the largest pharmaceutical bioavailability.