This study was performed to assess oral valganciclovir V-GCV (GCV pro-drug), 15 mg/kg bid for 6 weeks to 13 neonates with symptomatic congenital cytomegalovirus (CMV). We monitored plasma levels of GCV within 30 days of therapy: C(trough), and C(2h) (before and the 2 hours after administration), we performed viral assessment in plasma and urine and tolerability at baseline, and every fortnight. Pharmacokinetics showed GCV stable and effective plasma concentrations: mean C(trough) = 0.51 +/- 0.3 and C(2h) : 3.81 +/- 1.37 microg/ml. No significant variability was seen neither intra-patient nor inter-patients. One newborn discontinued therapy because of thrombocytopenia, another finished with a neutrophils count of 1,000/microl. At the end of therapy 6 out of 12 and 8 out of 12 newborns were negative for CMV in urine and plasma. The 4 newborns positive for CMV DNA showed a 90% reduction of pre-therapy values. Clinically, the 4 patients reporting hepatic disease and the 3 with thrombocytopenia recovered after 6 weeks of therapy. Eight newborns suffered from SNHL; at the 6-month follow-up no patients had worsened, 2 had improved, and no deterioration was reported in 3 newborns with chorioretinitis scarring. The paucity of adverse events, and the effectiveness and stability of drug plasma concentrations are the important findings of our study.