BACKGROUND: The COVID-19 pandemic and lockdown have had negative effects on students' mental health. However, little information is available regarding the frequencies of depressive symptoms and suicidal ideation during the post-pandemic period. We aimed to determine the effect of the COVID-19 pandemic on depressive symptoms and suicidal ideation among French university students. METHODS: In this comparative study, 4463 students were recruited during the pre-COVID-19 pandemic period (2013-2020) and 1768 students, during the post-COVID-19 pandemic period (2022-2023). Standardized frequencies of depressive symptoms and suicidal ideation were compared between the two time periods. Changes in the level of depressive symptoms and suicidal ideation between the pre- and post-pandemic periods, were then analyzed using interrupted time series analysis. RESULTS: Compared to participants from the pre-pandemic sample, participants from the post-pandemic sample had higher standardized rates of depressive symptoms (40.6 % vs 25.6 %) and suicidal ideation (29.3 % vs 21.1 %). Segmented logistic regression showed an about 50 % increased risk of depressive symptoms (aOR, 1.47; 95 % CI, 1.01-2.13) and a 100 % increased risk of suicidal ideation (aOR, 2.00; 95 % CI, 1.33-3.00) in the post-pandemic period. Before the pandemic, there was no significant time-trend for depressive symptoms (aOR, 1.002; 95 % CI, 0.999-1.006) and suicidal thoughts (0.999-1.006; aOR, 0.999; 95 % CI, 0.995-1.002). LIMITATIONS: Potential biases related to self-selection of participants in the study and information bias. History of depression and suicide attempt were self-reported. CONCLUSIONS: These findings reveal an alarming deterioration of students' mental health in the post-pandemic period compared to the pre-pandemic era.Read less <