BACKGROUND: Worry, a core feature of anxiety disorder, is shown in not only children with anxiety disorder but also normal children. This study was conducted to determine the relationship between worry and family environment factors, especially, perceived parental rearing and attachment styles among children. METHODS: Five hundred and nine children participated in this study among 549 children in third, fourth, fifth and sixth grades in two primary schools located in Seoul and Seongnam from October 2007 to December 2007. Forty children did not agree with participation (rejection rate: 7.3%). Their degrees of worry, attachment styles and perceived parental rearing were investigated with questionnaires. RESULTS: The reliability of a questionnaire asking children's worry, PSWQ-C and a questionnaire asking perceived parental rearing, modified EMBU-C was appropriate with internal consistency (Cronbach's alpha of PSWQ-C: 0.92, Cronbach's alpha of modified EMBU-C: 0.68~0.89). Around 22.4% of children had insecure attachment (avoidant or ambivalent attachment) and scores of worry were high in both girls and boys. When children perceived their parental rearing behavior as anxious rearing, they were classified to have ambivalent attachment in many cases by themselves. And when they perceived the rearing as rejection many of them were classified to have avoidant or ambivalent attachment by themselves. Worry showed a significantly negative correlation in the cases where children answered their perceived parental rearing as emotional warmth and showed a significantly positive correlation with rejective and anxious rearing. CONCLUSION: This study found that children's worry was closely related with their perceived parental rearing and attachment styles. If the children's attachment, which has been developed while they have grown up, was insecure and they did not perceive parental rearing as emotional warmth, the intensity of worry, a core symptom of anxiety disorder, increased.