Background:In terms of mental health, children are a particularly susceptible group of people. While mental health issues have affected people of all ages during this crisis, children are particularly affected by school closures and self-quarantine. The indirect effects of the epidemic on parents also cause distress and anxiety. Children and their carers may experience trauma from illnesses, financial hardships, societal upheavals, and deteriorating physical and mental health, creating a twofold source of stress. Aim: to improve mental health of children after covid-19 quarantine. Patients and Methods: This case study included 140 children divided into two groups: group A included 70 children recruited during the COVID-19 pandemic and group B was composed of children surveyed during the post-quarantine period. Both groups were subjected to assessment by SCARED questionnaire, while group A assessed although through measuring serum serotonin levels. Results:Children in group B had a significantly higher mean score of generalized anxiety symptoms, social symptoms, panic symptoms, and school avoidance subscales than group A with a p-value <0.05. In addition, group B had a higher mean score of separation anxiety symptoms subscale than group A with a statistically insignificant difference (p=0.103). Children in group B haa d significantly higher percentage of children with generalized anxiety symptoms, social symptoms, panic symptoms, and school avoidance than group A(p < 0.05).Based on the classification of the serum serotonin level, the majority of Group A had a normal serotonin level (58.6%), while 24.3% had a low level. Children with low serotonin level had a significantly higher percentage of children with generalized anxiety symptoms than other groups (p=0.020). Children with normal serotonin level had the lowest mean SCORED score (21.8±8.5). This difference was statistically significant (p=0.017). Conclusion:Children that were placed under a COVID-19 quarantine suffered from prolonged exposure to electronic screens, low blood serotonin levels, and anxiety symptoms, including panic disorder and generalized anxiety disorder. These impacts were both short- and long-term unfavorable.