Single oral doses of 250, 500, 750 and 1000 mg of sodium fusidate as one, two, three and four film-coated 250 mg tablets were compared in a cross over design trial with a solution dose of 500 mg in 12 healthy male volunteers. The effect of food on absorption of two-film coated tablets was also studied. Compared with the dose given as a solution, tablets gave complete oral absorption, the area under the curve (AUC) for blood concentration being virtually identical. After administration of 250, 500, 750 and 1000 mg the mean of the maximum serum concentrations (Cmax) was 11.6 +/- 1.1, 30.6 +/- 2.2, 48.1 +/- 3.0 and 65.2 +/- 4.2 mg/l, respectively, indicating a greater than expected increase in Cmax with increasing dose. This was also apparent with AUC, while there was a significant trend for beta, the terminal slope of the serum/concentration time curve, to decrease. Food significantly reduced Cmax and delayed Tmax but did not affect AUC or beta. Dosage had no effect on parameters of renal, hepatic or haemopoietic function but 25% of the volunteers complained of upper gastro-intestinal symptoms mainly at the highest dose studied.