Participation in PA is often diminished in children with CKD. Limited research exists on exercise tolerance/capacity but no studies to date have investigated lifestyle PA and its determinants in these children. The aim of this study was to investigate level of PA and potential physiological and psychological associations in a group of pediatric KTx recipients compared with CS. Twenty KTx and 33 CS participated. PA was measured by PAQ. HRQOL (PedsQL 4.0) and CY-PSPP were also measured. BMI and WC was recorded in all subjects; GFR, BP and immunosuppressants in KTx. Body measurements indicated the two groups were similar: 25% KTx and 24% CS had BMI >85th percentile. KTx were less physically active than CS in total exercise minutes (p = 0.005). CS reported higher HRQOL than KTx (p = 0.001). Higher perceptions of HRQOL were significantly correlated with higher number of steps/day in both groups (p = 0.034). KTx showed significantly lower perceptions of sports competence (p = 0.007) and physical conditioning (p = 0.001) than CS. Higher PAQ activity scores were significantly correlated with higher perceptions of body attractiveness (p = 0.019), Sport (p = 0.003) and Conditioning (p = 0.001). These results suggest that PA may play a role in overall well-being and HRQOL in KTx.