Introduction. Aquatic exercise is one of the most popular supplementary treatments for children with neuro-motor impairment, especially for cerebral palsy (CP). As water reduces gravity force which increases postural stability, a child with CP exercises more easily in water than on land. Objective. The aim of the study was to examine aquatic exercise effects on gross motor functioning, muscle tone and cardiorespiratory endurance in children with spastic CP. Methods. The study included 19 children of both sexes, aged 6 to 12 years, with spastic CP. They were included in a 12-week aquatic exercise program, twice a week. Measurements of GMFM (Gross Motor Function Measurement), spasticity (MAS ? Modified Ashworth Scale), heart rate (HR) and maximal oxygen consumption (VO2max) were carried out before and after treatment. The measurement results were compared before and after treatment. Results. GMFM mean value before therapy was 80.2% and statistically it was significantly lower in comparison to the same value after therapy, which was 86.2% (p<0.05). The level of spasticity was considerably decreased after therapy; the mean value before treatment was 3.21 according to MAS, and after treatment it was 1.95 (p<0.001). After treatment there was a statistically significant improvement of cardiorespiratory indurance, i.e., there was a significant decrease in the mean value of HR and a significant increase of VO2max (p<0.001). Conclusion. Aquatic exercise program can be useful in improving gross motor functioning, reducing spasticity and increasing cardiorespiratory endurance in children with spastic CP.