In business higher education, group project work plays an essential role. The purpose of the present study is to explore the relationship between the group heterogeneity of students' business project groups and their academic achievements at both group and individual levels. The sample consists of 536 freshmen from an International Business School in a Dutch University. The research has revealed that students' academic performances are positively correlated with their achievement in group projects at both individual and group levels. However, the group ethnic heterogeneity is negatively related with students' project scores. The findings may enable education practitioners to gain more insights into students' project work and manage students' group work more effectively.