Background: Over 50 million instances of serious injuries have been documented annually, while 1.2 million instances of mortality related to traffic accidents are disclosed around the world. This study aimed to establish the determinants of road traffic accidents among motorcycle riders in selected four Subcounties in Kitui County, Kenya. Material and Methods: The study employed a descriptive cross-sectional study design. Multi-stage sampling was employed to recruit study respondents for this study. Quantitative data was collected using a structured questionnaire while Key informant interview guides were used to capture qualitative data. Frequency and percentage were used to examine descriptive data while the association between two or more variables of interest was examined using logistic forward linear regression. Qualitative data was analyzed thematically. Results: From this study, there was a positive statistical association between environmental factors in motorcycle accidents (R=.392; p.05), translating to environmental factors being responsible for around 15.1% of possible motorcycle accidents. There was a positive statistical association between personal characteristics and motorcycle accidents (R=.291; p.05), translating to personal characteristics being responsible for around 8.5% of possible motorcycle accidents. Lastly, there was a positive statistical association between riding skills and motorcycle accidents (R=.342; p.05), translating to riding skills being responsible for around 10.2% of possible motorcycle accidents. Conclusion: From this study motorcycle accidents are a public health concern. In addition, environmental factors, personal characteristics, and riding skills were found to be statistically associated with motorcycle accidents.