A bioavailability study of 8 commercial pharmaceutically equivalent tablet formulations and a solution of metronidazole was conducted in groups of 10 subjects with single oral 250 mg doses. Although the solution gave significantly lower extents of bioavailability, the commercial tablets were not significantly different from the innovator) reference product. The slow rate of absorption for 1 formulation (F) was observed to be associated with long dissolution time. Individual elimination half-life differences (probably attributable to metabolism) were reflected in considerable intersubject differences in plasma metronidazole concentrations.