Background: Sunlight has been used for therapeutic purposes such as treating neonatal jaundice, nappy rash and best known sources to vitamin D which is crucial to the development of bone. However, the status of sunlight exposure practice and hindering factors is not well known in Ethiopia, and its district. Objective: to assess sunlight exposure practice and associated factors among infants in South Achefer district, North West Ethiopia. Methods: A community based cross-sectional study was conducted between August 15//2018 October 6, 2018. A stratifying random sampling method was to select 391 mothers with infants from eight selected Kebeles. The study participants were selected by systematic random sampling method, based on the sampling frame taken from the health posts from the selected kebeles. The data were collected by using face to face interview using a structured questionnaire. Data were entered to the computer using EPI-INFO version 3.5.3 and exported to the SPSS version 23 software for cleaning and analysis. Descriptive statistics were computed to describe study objectives. Bivariate and multivariable logistic regression analyses were used to identify factors associated with sunlight exposure practice. Odd ratio with 95% CI and p- value < 0.05 was used. Result- A total of 377 mothers with 96% response rate were involved in the study; the majority 84.4% mothers were living in rural and nearly three-fourth (72.2%) of mothers were below primary education level. Nearly two-third (64.6%) of mothers had poor sunlight exposure practice to their infants. In multivariable logistic regression analysis, mothers who had information on sunlight exposure AOR=19.755(10.027, 38.919), and mothers who were not fear of sunlight exposure AOR=11.869(6.002, 23.472) as a result of sunlight exposure practice showed a statistical significant association. Conclusion and recommendation-Mothers poorly practiced the sunlight exposure to their infants for various reasons. Getting information and fear of sunlight exposure were statistically significant variables associated with sunlight exposure practice. Therefore, continuous health education and counseling of mothers about the importance and procedure of sunlight exposure to their infants is vital to improve the practice in the study area. Key words: infants, mothers, sunlight therapy practice, associated factors, South Achefer District, Ethiopia