Background:rnSkeletal metastases account for 70% of all malignant bone lesions and are seen in vast number ofrnprimary cancers. Lung cancer, breast cancer, renal carcinoma and prostate cancer account forrnapproximately 80% of all skeletal metastases.rnCT scan imaging has an important role in the detection, diagnosis, prognosis treatment, planningrnand follow up monitoring of bone metastases.rnSubstantial proportion of patient with advanced cancer and bone develop skeletal related eventsrnincluding pathologic fracture, spinal cord compression,myelosuppression and hypercalcemiarnwhich usuallyassociated with moderate or severepain.rnObjectives:rnTo determine pattern and distribution of skeletal metastases in patient with known and unknownrnprimary cancer by using CT scan at Tikur Anbessa teaching referral hospital.rnMethod:rnProspective cross-sectional descriptive study of all patient with skeletal metastases diagnosed byrnCT scan followed by using data collection sheet (questionnaires) and medical records duringrnstudy period at Black Lion Hospital from October 2018 to July 2019.rnResult:rnA total of 140 patients with known or unknown primary tumor with bone metastasis werernincluded in the study from October 2018 to July 2019 GC. 81 0f them were female and 59 werernmale.The mean age at presentation was 52 years +/- 14.75(age range of 37.25-66.75years) andrnmajority of the patients were found in age group of 40-60(42.9%)years.Among the involvedrnbone the most common affected was spine (62.1%), followed by pelvis (41.2%).The mostrncommonly known primary cancers metastasis to bone were breast (30.7%) followed by lungrn(29%) and prostate (15.7%) tumors.Lytic type (51%) of the bone lesion is the frequentrnmorphologic type followed by mixed (34%) and sclerotic (17%).Among the studied patientsrn(65%) patients had bone pain symptom while (19.3%)had pathological fracture and (15.7%)patients had spinal cord compression symptom.rnDiscussion:rnMajority of patients during the study period were female and the mean age of prestation was 52rnyears +/-14.75. Among the primary tumors breast, lung, prostate, renal and thyroid cancer werernthe common tumors identified in our study. In this study spine was the most common bonerninvolved followed by pelvis and ribs and sternum. When we see the morphology of bone lesionrnidentified on CT scan lytic is the most common followed by mixed andscelrosis.Pain was thernmost common clinical pentation of the studied patient.