Background: Chemotherapy is among the standard treatments for cancer and leukopenia,rnneutropenia, febrile neutropenia and lymphopenia are the most common side effects. These siderneffects have been reported to be associated with substantial morbidity, mortality and healthcarerncosts.rnObjectives: To assess the prevalence of chemotherapy induced leukopenia (CIL) in solid cancerrnpatients at St Paulâ€Ÿs Hospital Millennium Medical College Oncology unit, Addis Ababa,rnEthiopia.rnMethods: An institution based cross sectional study was performed at St Paulâ€Ÿs HospitalrnMillennium Medical College Oncology unit from February 1st 2020 to May 2020. Usingrnconvenient sampling technique, 92 patients, who were diagnosed for any type of solid cancer,rnwere recruited in this study. EDTA whole blood was collected before each cycle of treatmentsrnand analyzed for complete blood count (CBC) using Beckman coulter analyzer before and afterrnthe initiation of chemotherapy. The laboratory analysis was done for five times Data werernentered; cleared and analyzed to match the objectives. Chi-square statistics were employed and prnvalues less than 0.05 were taken as statistically significant.rnResults: Among the 92 patients who participated in this study, the following adverse effectsrnwere observed after the use of various chemotherapy regiments in the five cycles. The mostrncommon adverse effects of Chemotherapy Are Leukopenia 80.4%, Neutropenia 70.7 %, FebrilernNeutropenia 50% and Lymphopenia 88%. occupation and ECOG have a significant association with rnthe occurrence of hematological toxicities with (p=0.011) and (P=0.013) respectively. Also majority ofrnhematological toxicities are caused by Adriamycin + cyclophosphamide. rnConclusion: Even though chemotherapy is the standard treatment for cancer patients, it causesrnleukopenia, neutropenia, febrile neutropenia and lymphopenia which may cause delaying of rntreatment, morbidity and mortality.