Ganciclovir (DHPG) was used in 32 renal transplant recipients with proven cytomegalovirus (CMV) disease. Mean time of CMV occurrence from grafting was 49 days. CMV disease was recognized on the combination of both clinical signs and histological or virological findings. DHPG treatment, adapted to renal function was given for 14 days and a pharmacokinetic study was performed at days 1, 7 and 14. Twenty nine patients, 10 of whom has severe to moderate disease, were improved by treatment. Three patients died, 2 of them with severe pulmonary and hepatic diseases. Few adverse effects were observed (leucopenia: n = 7, thrombopenia: n = 2, abdominal pain: n = 1). CMV was no longer found in virological samples in 80 percent of the patients. Maximal plasma concentration of DHPG (9.3 +/- 0.3 micrograms/ml, m +/- SEM) was reached at the end of the one hour infusion and decreased according to a biexponential model. The half life of elimination was 3.35 +/- 0.32 hours, the metabolic clearance 128 +/- 7 ml/min and the distribution volume about 50 percent body weight (0.48 +/- 0.02 l/kg). The clearance of DHPG was greater than creatinine clearance, and was linearly correlated with it, suggesting that renal elimination was important, both by glomerular filtration and tubular secretion. These results indicate that DHPG is effective and well tolerated for the treatment of CMV disease in renal transplant recipients. Renal elimination of the drug requires dosage adjustment to renal function.