BACKGROUND: University students are faced with several stress factors affecting their mental health. Therefore, the first year at university is a period that calls for careful attention and research. AIM: The aim of this study is to evaluate the effect of laughter yoga on mental symptoms and cortisol levels in nursing students. METHODS: This study is a randomized controlled study employing a pre-/post-test design with a control group. A total of 75 healthy university students were assigned to the intervention group and control group. The Brief Symptom Inventory was applied to both groups before Session 1 and after Session 8. Saliva samples were taken from the students to measure their cortisol levels before and after each session. RESULTS: Evaluation of the mean scores obtained from the Brief Symptom Inventory before and after the intervention showed a significant decrease in the scores between groups (P < 0.05). In three out of the eight sessions, there was a significant decrease in the intervention group compared with the control group regarding the mean values of pre-test and post-test salivary cortisol levels (P < 0.05). CONCLUSION: Laughter yoga can provide an effective means to help first-year nursing students cope with stress and reduce mental symptoms.