Introduction: As the COVID-19 pandemic continues to unfold, rapid global efforts to develop and test vaccines against SARS-CoV-2 have started. Adverse events after immunization are a common issue seen in many vaccines. This study aims at finding the adverse events following the first dose of CovishieldTM vaccine administered to the staffs at two health institutions in Kathmandu. Methods: This was a descriptive cross sectional study conducted among the staffs at National Public Health Laboratory and Sukraraj Tropical and Infectious Disease Hospital, Kathmandu between February to April, 2021. It included 162 participants who had taken the first dose of CovishieldTM vaccine. Ethical approval was taken from Nepal Health Research Council. Statistical Package for the Social Sciences were used for analysis. Results: Various adverse events were seen in 139 (85.8%) participants which were all minor events. None of the participants developed serious adverse events. Very common adverse events experienced were Injection site pain 116 (71.6%), myalgia 76 (46.9%), chills 68 (42%), headache 65 (40.1%), fever 54 (33.3%), dizziness 43 (26.5%) and nausea 20 (12.4%). Similarly, the range of time period from onset to recovery of adverse event was different for different adverse reactions. Conclusions: The adverse events following first dose of CovishieldTM vaccine were all minor reactions with commonest being injection site pain followed by myalgia, chills, headache and fever.