Background: Mid-level health workers are deployed in a large proportion with the expectation of similar patient outcomes as with physicians. Mid-level practitioners are Health Assistants and Auxiliary Health Workers who provide clinical care at remote locations. National Health Training Center has been providing 60 days in-service Mid-level Practicum training since 2009 AD for the mid-level practitioners with the aim to enhance quality of patient care in Nepal. Methods: An observational study conducted using retrospective data from onsite follow-up assessment of 180 Mid-level Practitioner from 18 districts of Nepal between July 2015 to June 2019. The retention of competency onsite follow-up was calculated as percentage of assessment score at the end of Mid-level Practicum training. Percentage retention of competency and association of retention with factors were analyzed using independent t-test. Results: Majority of participants were male (85.6%), and working in a Health Post (84.4%). Average clinical competency retention in each domain at their work place was 68.79% in knowledge, 73.80% in patient encounter skill, 82.84% in clinical decision-making skill and 87.58% in clinical procedure skill. Higher age groups, longer years of experience and participants from Terai region found to be associated with lower retention of knowledge. A better enabling environment and higher case load retained higher patient encounter skill. Conclusions: The competency retention among Mid-level Practicum trained mid-level health workers was found to be higher. Factors found associated with competency retention were age, geographic region, years of experience, case load and enabling environment. Keywords: Competency retention; knowledge; MLP; skill.