The COVID-2019 pandemic has presented a new situation affecting not only the somatic but the mental health of people worldwide and exposing the world including healthcare professionals to a challenge never experienced before. Therefore its effects on mental health, although can be estimated, but cannot be predicted, thus we are only halfways prepared for understanding as well as screening, preventing and treating the pandemic-related mental health problems. For this reason, the Mental Health Sector of the Scientific Researches Institute of the Pan-Hellenic Medical Association prepared a large, international online, general population study with participation from over 42 countries, assessing various aspects of general mental function, needs and behaviors that could occur during the COVID-19 outbreak, as a result of either the outbreak itself or the social measures adopted in order to control it. While the study is ongoing, here we present the first descriptive results from the Hungarian study sample including 738 adult participants collected during the first wave of COVID-19-associated lockdown, focusing on differences in the effect of COVID-19 on psychological and lifestyle measures, as well as attitudes towards the pandemic between mentally healthy participants and people with mental disorders.