Objective: Oral and dental problems are important issues in patients suffering from hematologic malignancies. This study aimed to assess the efficacy of supragingival irrigation with chlorhexidine in improving the oral health status of patients with hematologic malignancies.Methods: This randomized, single-blind, controlled clinical trial, included 32 patients suffering from blood dyscrasia and hospitalized in Imam-Reza Hospital, Mashhad, Iran. Participants were randomly allocated to intervention and control groups. The control subjects received routine dental care by cleaning their teeth daily with sterilized gauze soaked in normal saline. For the intervention group, supra-gingival irrigation with chlorhexidine was performed in addition to routine dental care. The Debris Index Simplified (DI-S) part of the Oral hygiene index-simplified (OHI-S) index was recorded in all patients at baseline (T0), one (T1), two (T2), and three (T3) weeks later. The World Health Organization (WHO) scale was used to assess oral mucositis.Results: DI-S decreased significantly in the intervention group (P