Studies in Hong Kong indicated that there is a tendency for young children to use internalizing as a means to cope with their daily difficulties. Mother–child relationship has been seen as a factor affecting a child's adaptive coping skills. In this study, we explored the prevalence of internalizing problems among primary school children in Hong Kong, as well as the mother–child relationship that contribute to children's internalizing problems. Data used to assess the internalizing behavior among 1598 primary school children were collected from their mothers. The estimated prevalence of internalizing problem was 11.4%. This prevalence was based on the cutoff point for internalizing disorders according to the Child Behavior Checklist (CBCL). The CBCL internalizing score was significantly correlated with mother–child relationship as measured using the Parent–Child Relationship Questionnaire (PCRQ). Results from the PCRQ indicated that children's internalizing problems were positively correlated with mother's use of verbal punishment and rejection as well as their possessiveness and protection on their children. On the other hand, a nurturing and intimate relationship between mother and child was an important factor contributing to the development of mentally healthy children. Implications of this study and suggestions for further research were discussed.