INTRODUCTION: The aim of the study was to investigate mental health in university students in Greece, during lockdown due to COVID-19.MATERIAL AND METHODS: The data were collected online and anonymously, during lockdown; they included 1104 females (aged 22.08±4,96) and 431 males (aged 22.35±3.11). The analysis included transformation of the data with post-stratification method, descriptive statistics, Chi-square tests, Factorial Analysis of Variance and Relative Risk ratios RESULTS: : The results suggest that during, lockdown major depression was present in 12.43% with 13.46% experiencing severe distress. Risk factors were female sex, history of self-injury, suicidal attempts and following theoretical studies (RR=2-5.71). Conspiracy theories were accepted by 20-68%, with students of theoretical studies manifesting higher rates.DISCUSSION: The results of the current study confirmed that students are at high risk to develop depression and suicidality in relation to the COVID-19 outbreak. They also identified specific risk factors and pointed to the role of believing in conspiracy theories in copying with stress. They also identified populations with higher prevalence of these beliefs. Further targeted research is necessary as well as targeted intervention in vulnerable groups but concerning mental health as well as the reduction of believing in conspiracy theories.