Purpose - An increasing number of people are migrating within the borders of China. Some migrants have to leave their children behind, and 58,000,000 children are estimated to be living as left-behind children. Earlier studies have found severe mental problems in left-behind children, but different factors could influence their mental health. The aim of this study was to investigate the mental health of these left-behind children and to determine possible influencing factors.

Design/methodology/approach - Data for this study were collected in one province of the P R of China with a validated instrument, the Strengths and Difficulties Questionnaire (SDQ) to investigate behavior in 13- to 15-year old children.

Findings - No significant difference was found in total difficulty score and in any subscale score of SDQ when we compared left-behind children with children who were not left behind. A significant difference in emotional difficulty subscale score was found between girls who were left behind and girls who were not. Some socio-economic factors such as poor family economy and living with relatives, friends or grandparents, were identified as risk factors.

Originality/value - When strategies for support of the mental health in left-behind children are developed, they will need to be individualized according to the gender, social and economic situation and focused on emotional and conduct problems.