The aim of this review is to determine whether physical fitness, assessed by peak oxygen uptake (VO(2peak)) measurement, is reduced in survivors of acute lymphoblastic leukemia (ALL) compared to healthy children. A systematic literature search (up to June 2004) was performed using Medline, Sportdiscus, Cinahl, Embase, Cochrane and PEDro database and reference tracking. The VO(2peak) (ml kg(-1) min(-1)) reached during a maximal exercise test until volitional exhaustion was used as the main outcome for this review. In all, 17 studies were identified in the literature. Data from three studies (102 ALL survivors, age ranging from 7 to 19 years) were pooled in a meta-analysis. Although there was a significant heterogeneity between the included studies (P=0.0006), the standardized mean difference (SMD) value of -0.61 (P=0.07) indicated that VO(2peak) tended to be reduced in survivors of childhood ALL compared to healthy control subjects, that is, decrease of -5.97 ml kg(-1) min(-1) (95% confidence interval (CI): (-12.35, 0.41); P=0.07) or -13% (95 % CI: (-27, 0.004)). Physical fitness tends to be reduced in survivors of ALL during childhood, which suggests the need for this population group to engage in regular physical activities with the purpose of increasing their functional capacity. Although more research is needed, this functional improvement might ameliorate the quality of life of ALL survivors as physical and outdoors activities are an essential part of daily routine during childhood.