We investigated the efficacy of dexamethasone plus diclofenac eye drops as prophylaxis for conjunctivitis induced by high-dose (HD) cytarabine (Ara-C). Sixty patients were randomized to receive either dexamethasone (group A, n=29) or dexamethasone plus diclofenac (group B, n=31). Conjunctivitis was experienced by 13/29 (45%) patients in group A, and 4/31 (13%) patients in group B (p<or=0.009). Twelve out of 13 patients in group A who developed ocular toxicity had grade 2-3 conjunctivitis whereas only one of four patients affected in group B experienced a similar grade of conjunctivitis. The incidence and severity of HD Ara-C-induced conjunctivitis are significantly reduced by combined dexamethasone/ diclofenac prophylaxis.