Thirty two allogeneic bone marrow transplant (BMT) recipients, aged 16-55 (median 35), with CMV antigenemia (= > 5 positive cells) developing at a median interval from BMT of 49 days, were given combined treatment with foscarnet and ganciclovir for 15 days. Maintenance was given with foscarnet and ganciclovir on alternate days for an additional 2 weeks. 31/32 patients were on cyclosporin 30 on systemic antibiotics and 9 were on intravenous amphotericin Median laboratory values on day 1 and 15 of treatment were respectively creatinine 1.0-1.1 mg%; WBC 5.7-4.1 x 10(9)/l; platelets 78 72 x 10(9)/l. All patients cleared CMV-antigenemia by day +15, though 5 reactivated on and 14 off maintenance: the dose of foscarnet (but not ganciclovir) received in the first 15 days was significantly lower in patients reactivating within 30 days (p = 0.0002). Six patients died, one with i.p., one with multiorgan failure, and four with infections. Eighteen patients survive 119-1051 days post-transplant. The actuarial TRM at 1 year is 23%. This study shows that combined foscarnet-ganciclovir is one therapeutic option for allogeneic BMT recipients developing CMVAg-emia with a high number of CMVAg+ cells: treatment can be given together with cyclosporin and antibiotics with appropriate dose reductions; it produces prompt clearing of CMV infection, and may reduce transplant related mortality when compared to single agent therapy.