Background: Sinonasal area is a host to various neoplastic and non- neoplastic lesions. The presenting symptoms of sinonasal lesions are similar and pose difficulty for diagnosis based on clinical features and advanced imaging modalities, which makes histopathology the principal diagnostic tool approach for these lesions. The aim of this study is to determine the various histopathologic types of Sinonasal lesions, their classification and relative distribution with regards to age and sex in our setting. Materials and Methods: A retrospective cross-sectional descriptive study conducted on 306 cases of sinonasal lesions over the period from January 2016 to August 2020. All the sinonasal tissues were received and diagnosed at histopathology section of Department of Pathology in Tikur Anbessa Specialized Hospital, Addis Ababa, Ethiopia. The Pathology reports were collected from the pathology data archives; and the variables of study were extracted by using a data extraction sheet, and data analysis was done using SPSS version 26.0. Results: Most affected age group was 21-30 years 81(26.5%). Male predominance was observed with M: F ratio of 1.4:1.Nasal cavity was the commonest anatomical site involved 237(77.5%).There were 137(44.8%) Non-neoplastic lesions and 169(55.2%) Neoplastic lesions. Inflammatory Sinonasal Polyps 100(73.0%) were the most common among non-neoplastic lesions; inverted Sinonasal Papilloma 34(41%) the most common among the benign neoplastic and squamous cell carcinoma and nasopharyngeal carcinoma accounting for 21(25.6%) cases each, were the commonest malignant lesions. Conclusion: clinical findings and advanced image modalities can reach to a presumptive diagnosis for the sinonasal lesions but histopathology remains the gold standard for categorizing and diagnosis of non-neoplastic and neoplastic lesions of sinonasal tract.