Background and Objectives: The BCG vaccine scar is often used as a surrogate marker of adequate vaccination, indicating correctness of the technique and effective vaccination. This study reports the prevalence of observed BCG scars and studies potential determinants in Health Care Workers (HCW) from Cabo Verde, Guinea-Bissau, and Mozambique. Methods: Observational cross-sectional study of baseline data collected within the BCG-COVID-RCT trial [1] in Cabo Verde, Guinea-Bissau, and Mozambique. Participants were HCW working in hospitals and health centres. Presence of BCG scar was by a physical assessment of BCG scars including number and location(s) of observed BCG scars and self-reported vaccinations with BCG. Prevalence rates adjusted for age, gender, occupation, number of times vaccinated with BCG, chronic disease, and time of birth in relation to BCG vaccination policy were computed using Poisson regression with robust variance for the outcome observed BCG scar. Analyses are presented by country, controlling for differences in local BCG vaccination strategies. Results: The prevalence BCG scar was 85.5% in Mozambican HCW, 75.0% in Guineans and 70.0% in Cabo Verdean HCW. The prevalence of scars was not associated with any of the studied background characteristics: gender, age, morbidity and occupation. After controlling for gender, age and occupation, having a BCG scar was found to be associated with having been born after the implementation of universal BCG vaccine at birth, being vaccinated more than once and being overweight or obese only for Guinea-Bissau. Conclusions: Results demonstrate a relatively high prevalence of BCG scar among HCW in Cabo Verde, Guinea-Bissau, and Mozambique. There seems to have been catch-up programs for people born before the Introduction of BCG at birth in Mozambique and CV. Between 15-30% of the studied HCW still do not have a BCG scar. The role of a BCG scar for subsequent health in adults should be investigated. Links: ------[1] https://clinicaltrials.gov/ct2/show/NCT04641858