Objective To assess the screening and isolation measures for preventing coronavirus disease 2019 (COVID-19) infection from newly admitted patients into a pediatric oncology ward. Methods We retrospectively analyzed 44 patients with established hematologic malignancies admitted for chemotherapy from January 23 to March 27, 2020 in the Department of Pediatric Hematology of Tongji Hospital, Wuhan. Every patient and their caregivers were well educated on personal protection and put it into effect at home and in hospital. Screening for COVID-19 of all the patients and caregivers before admission was performed. Both clinical features and screening results including chest computerized tomography (CT); nucleic acid testing of nasopharyngeal, oropharyngeal or anal swabs; and quantitative antibodies (IgM and IgG) detecting of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) of these patients were described. Results The results of nucleic acid and antibodies (IgM and IgG) testing of all the 44 inpatients and their caregivers were negative. Abnormal chest CT images were observed in six symptomatic patients, while chest CT images of their caregivers did not show the changes related to viral pneumonia. These symptomatic patients all recovered after antibacterial combined with antifungal treatment, but without any antiviral agents. Conclusions COVID-19 infection could be prevented in pediatric patients with malignancies if proper protective measures were implemented. For patients presenting suspicious symptoms, comprehensive examinations should be carried out.