Background: To improve collaborative learning and discussion, problem-based learning (PBL) curriculum usually assigns students to small groups. We design group report contest (GRC) to improve inter-group learning. Materials and methods: The "Medicine and Society" PBL course assigned the second year medical (M2) students to 16 groups. In the past, there were no interactions between groups. Since 2011, students must present their final group reports in front of the whole class. The presentations should focus on what they have learned during the semester. Tutors and students jointly decided the group report scores. We sent questionnaires with 5-point Likert scale to teachers and students. We analyzed the scores given to each group and the responses to the questionnaires. Students' or teachers' viewpoints were compared. Results: Students decided their topics, shared their thoughts, and gave their presentations cooperatively. The rankings of the group report scores given by students or tutors had great similarity. Both students and tutors scored group 15, 2, 6, 7, and 5 as the top five groups and the group 12 as the bottom one group. Majority of students and teachers favored (Likert scale 4 and 5) that GRC may enhance students' cooperation, stimulate students' creativity, enhance students' understanding about PBL, provide opportunity for students to learn from other groups, and enhance the tutors to understand the learning styles of other groups. Conclusions: During GRC, students collaboratively demonstrate what they have learned in the PBL classes. GRC arouses students' interests and enhances their learning.