Introduction:The COVID-19 pandemic has impacted populations internationally, through infections and consequences of infections, and by the countermeasures to prevent the spread of the coronavirus. Concerns exist surrounding the impact of the COVID-19 pandemic on the mental health of youths in the Netherlands. Consequently, we studied quarterly trends and risk factors of suicidal ideation among Dutch youths from September 2021 onwards.Method:The Network GOR-COVID-19, a research group consisting of different organizations, monitors the effect of the COVID-19 pandemic on population health. As one element of this monitoring, quarterly data collections have been undertaken since September 2021 from a panel of youths (12 – 25 years of age) representative of the Dutch population. Online questionnaires collect data on self-reported health and wellbeing. We analyzed a selection of demographic, social activity, and mental health variables as potential risk factors for self-reported suicidal ideation in the previous three months. We assessed trends, performed longitudinal analyses, and conducted logistic and random forest regressions per quarterly round of data collection. Analyses were weighted for age, sex, educational level, and province where appropriate.Results:Approximately 4,500 youths participated in each quarterly questionnaire, with some participating more than once. Results showed substantial increases in self-reported suicidal ideation during and immediately after the third lockdown in the Netherlands in December 2021, rising from 9% to 17%, then slowly decreasing to 16% in May/June 2022, and to 13% in September 2022. In all multivariable analyses variables relating to mental health were indicated as risk factors. The strongest associations were seen in those experiencing mental health complaints and loneliness. Demographic variables were not strongly associated with suicidal ideation.Conclusion:The monitoring conducted by The Network GOR-COVID-19 enables the tracking of trends in the impact of the COVID-19 pandemic on the mental health of Dutch youths in The Netherlands.