Physical fitness is an essential feature of overall health. Our objective was to compare the physical performance between nontransplanted acute lymphoblastic leukemia (ALL) patients (study patients), healthy controls, and ALL patients after stem cell transplantation (SCT). Forty-five ALL patients (median age, 13.3 y) treated without cranial irradiation were compared with 34 ALL patients (12.0 y) treated with SCT and total body irradiation and 522 age-matched and sex-matched controls. Their physical performance was assessed by 6 muscle tests measuring speed and dynamic endurance, flexibility, acceleration, maximal speed, and speed differentiation. The patients were tested at a minimum of 3 years after treatment. The muscle test results of the study patients did not differ from that of the healthy controls. The study patients had normal body mass indexes (BMI). Only 42% of them exercised at least once a week. Those who exercised >3 times a week and those with a BMI below median had better results. SCT patients had inferior results in 4 out of 6 tests. The physical performance of nontransplanted ALL patients did not differ from that of healthy controls. A higher physical exercise activity and a BMI below median positively correlated with better muscle performance, supporting the importance of encouraging ALL survivors to exercise and avoid obesity.