The study investigated Afghan undergraduate students’ perceptions of positive and negative effects of coeducation. It also examined the impact of students’ gender and ethnicity on their perceptions. A survey questionnaire was used to collect data from 230 randomly selected students from Takhar University. The authors utilized descriptive and inferential statistics to analyze the data. The results showed that students had positive attitudes towards coeducation. They believed that coeducation had both personal and social effects such as improving students’ academic confidence, communication skills, preparing them for real life, promoting gender equality and reducing gender biases and stereotypes. However, less than half of students believed that coeducation had negative effects, e.g., distracting students and male students’ domination of class activities. Moreover, the findings revealed that students’ gender had a significant impact on their responses; female students’ attitude towards coeducation was stronger than that of male students. However, students’ ethnicity did not significantly impact their responses.