Acute lymphoblastic leukemia (ALL) is one type of cancer mostly found in children. Pain and fatigue have a close relation due to cancer and the treatment process. Previous studies only dealt with the scale of pain and viewed pain as a contributing factor in triggering fatigue. Nevertheless, how pain, especially in ALL children, could trigger fatigue especially during the chemotherapy phases is not yet discussed further and in-depth. This current research aimed to analyze the relationship between the quality of pain and fatigue in ALL children 1-3 days after chemotherapy. The research was carried out using a cross sectional design with a consecutive sampling technique. There were 44 ALL children in Jakarta aged 7-18 years as the samples. The measuring instruments used in this research were the Brief Pain Inventory (BPI) questionnaire to measure the quality of pain and the Allen-Child Oncology Fatigue questionnaire to measure fatigue. The obtained mean scores for the quality of pain was 1.63932, and the mean score for fatigue was 9.25. The results of this research also showed that there was a significant relationship between the quality of pain and fatigue (p = 0.006), relapse status and fatigue (p = 0.058), and companion when in pain and fatigue (p = 0.016) in children with acute lymphoblastic leukemia. These research results recommend the importance of pain assessment and the management of pharmacological and non-pharmacological combinations for post-chemotherapy pain to reduce fatigue in cancer children.