Background: A cancer diagnosis can affect the emotional health of patients, families, and caregivers. Common feelings during this life-changing experience include anxiety, stress and depression. Aim: to assess the psychological condition of children having acute lymphoblastic leukemia undergoing chemotherapy. Design: Descriptive exploratory design. Settings: This study conducted at the In-Patient Pediatric Hematology Oncology Departments Children's Cancer Hospital Foundation- Egypt, Cairo (57357). Sampling: A purposive sample comprised of 100 children suffering from ALL undergoing chemotherapy. Tools: Part 1: An interviewing questionnaire to assess children sociodemographic. Part 2: Psychological assessment scale for children to assess (1) depression (2) anxiety (3) stress. Results: This study revealed that more than third of studied children were in the age range 6-<10 years while more than two thirds of children were males., more than third of studied children had moderate depression, while less than quarter of studied children had severe depression. Conclusion: from the findings of the current study it can be concluded that the anxiety, depression and stress of the majority of studied children were affected by cancer and chemotherapy. Recommendation: Design psychological assessment sheet regarding stress, anxiety and depression assessment among children with acute lymphoblastic leukemia and being a routine for nurses to apply.