The impact of definitive laboratory diagnosis on overall patient outcomes can be realized with better quality of laboratory results. However, there is limited availability of laboratory professionals with the knowledge, skills and experience in quality management system (QMS). We designed and evaluated the impact of a mentorship model used as on-the-job training in QMS in medical laboratories in Africa. 41 mentors were trained and deployed into 82 laboratories from 7 African countries, spent 3-6 weeks in the laboratory per visit, with a period built in-between visits where the mentor was absent to provide an insight into how well the laboratory is able to sustain, or extend improvements in the absence of the mentor. Laboratory performance was measured using the WHO/AFRO SLIPTA checklist. A survey questionnaire was used to collect data on knowledge, attitudes and behavior of deployed mentors as a means of checking their knowledge and implementation of the model. Results indicate that a structured mentorship program is effective in training laboratory staff QMS with time spent onsite, management support and training of the mentors as significant predictors of success.