Background: Africa is a region hardest hit by the Human Immunodeficiency Virus (HIV)rnamong other continents on the globe with the highest rise of the infection in the eastern andrnsouthern parts. Besides, the development of Pretreatment drug resistance (PDR) is becomingrnan obstacle to the success of antiretroviral therapy (ART). Despite ART scale-up, there is onlyrnlimited information with regard to HIV-1 PDR in Ethiopia. Moreover, with increasingrnmovement of people, HIV-1 variants other than the predominant subtype C may be introducedrnand intermixed from the neighboring countries. Therefore, this study was aimed to assessrnHIV-1 Genetic Diversity and Pre-treatment Drug Resistance Mutations among recentlyrndiagnosed HIV-1 Infected Antiretroviral-Naive individuals in Addis Ababa, Ethiopia. rnMethod: Institutional based cross-sectional study was conducted from June 2018 up tornDecember 2018 in Addis Ababa, Ethiopia. Plasma samples (n=72) from ART-naive studyrnparticipants were collected for sequencing of partial HIV-1 pol region covering the completernprotease (PR) and partial reverse transcriptase (RT) regions (nucleotides 2253 to 3539 ofrnreference strain HXB2) using in-house assay. Both Stanford University HIV drug resistancerndatabase (Stanford HIVdb) and the International Antiviral Society-USA (IAS-USA) 2019rnmutation list Algorithms were used to assess the presence of PDR mutations. rnResult: From 72 eligible plasma samples, 75% (54/72) of them were successfully amplified. rnOut of this, 51/54 (94.4%) were successfully sequenced and analyzed. According to thernStanford HIVdb and IAS-USA mutation list, 9.8% (5/51) of analyzed samples had at least onernPDR Mutation. PDR mutations to Non-Nucleoside Reverse Transcriptase Inhibitor (NNRTIs)rnwas the most frequently detected mutation (7.8% and 9.8%, according to Stanford HIVdb andrnIAS-USA Algorithm respectively) followed by Nucleoside Reverse Transcriptase Inhibitorsrn(NRTIs) (1/51, 2% by both Algorithms) and Protease Inhibitors (PIs) (1/51, 2%, According tornthe Stanford HIVdb only). One individual had PDR mutations that confer resistance to NNRTIrnand NRTI simultaneously. In addition, a high rate of polymorphism was observed both in thernPR and RT regions. With regard to HIV-1 genetic diversity, phylogenetic analysis showed thatrnall 51/51 (100%) of the study participants were infected with subtype C virus. rnConclusion and Recommendations: This study presents additional evidence for increasedrnlevel of PDR and persistence HIV-1C clade homogeneity after 15 years of the rollout of ARTrnand 3 decades of HIV-1C circulation in Ethiopia, respectively. Therefore, routine genotypicrndrug resistance testing is warranted for successful ART programs and the overall preventionrnof HIV transmission in the country to support the global efforts in achieving the third 90 ofrnthe UN target.