Purpose: The purpose of this study was to compare psychosocial adjustment in children aged 4-11 years with cancer between on and off treatment. Method: The data was collected from parents of children with cancer through interviews with structured questionnaire at the pediatric outpatient department and inpatient ward of one university hospital located in Seoul. The instrument were the Child Behavior Check List(CBCL) developed by Achenbach(1991) and revised to standardize for Korean children by Oh et al(1997). Result: Total behavior problem score for children on treatment was greater than the score off treatment but there was no significant difference. Children on treatment reported higher levels of depression/anxiety, withdrawal, internalizing scores than children off treatment. Social competence score of children off treatment was greater than the score on treatment and the difference of school performance score of children between on and off treatment was not significant. The scores on the withdrawal, somatic complaints, social immaturity, internalizing scales in the cancer group including both on and off treatment was greater than normative findings in the general population. The scores on the school competence of children off treatment were lower than the norms for healthy children. Conclusion: Findings from this study support the importance of nursing interventions to facilitate the adjustment of children with cancer both on and off therapy.