Purpose: To determined the prevalence of the child labor among male primary school students in Mukalla district in Yemen. Methodology: A cross-sectional study was designed to collect data from 5 th grade to 9 th grade primary school students in Mukalla city during the year 2015/2016. Results: The study showed a high prevalence of child labor among school children in Mukalla city (54.2%) where the common reason of child labor is that children have the interest to help their families (69.9%). About (35%) of students reported that they exposed to different kinds of abuse in their owner's place. Child labor affects negatively on their school's achievements and about 20.7% of them thinking to leave school. Educational level of parents did not indicate significant association with child labor (p-value 0.11) Conclusion: High prevalence of child labor may affect on their school achievements and being a predisposing factor to school drop-out.