Forty kidney-transplanted patients with hypertriglyceridemia, under treatment with cyclosporine alone or associated with other immunosuppressive drugs, were treated with gemfibrozil. This drug, for a long-term treatment (ranging from 4 to 6 months), was able to decrease hypertriglyceridemia and did not modify either polyclonal (P) and monoclonal (M) cyclosporine blood levels or P/M ratio. These data seem to exclude an effect of gemfibrozil on cyclosporine blood concentrations. Therefore, the use of gemfibrozil in kidney-transplanted patients does not require modifications of cyclosporine dose.