PURPOSE: This study examined the effects of breathing exercise in the water on the pulmonary function and maximum phonation time in children with cerebral palsy. METHODS: The subjects were 24 children with cerebral palsy at GMFCS levels I-III, who were allocated randomly to either the aquatic breathing exercise group or general breathing exercise group 12 subjects per group. Each subject was required to complete 40 minutes of exercise twice a week for eight weeks. Those in the aquatic breathing exercise group performed aquatic breathing exercise, whereas those in the general breathing exercise group performed general aquatic exercise. RESULTS: Significant differences in $FEV_1$, PEF, VC, TV, ERV, and maximum phonation time were observed in the aquatic breathing exercise group after intervention, but there were no significant differences in either FVC, $FEV_1/FVC$, IC, or IRV. In the general breathing exercise group, there were no significant differences in the FVC, $FEV_1$, $FEV_1/FVC$, PEF, VC, IC, TV, IRV, ERV, and maximum phonation time after intervention. In terms of the pulmonary function, the two groups showed a significant difference in the change in $FEV_1$, PEF, and TV after intervention, but not in the FVC, $FEV_1/FVC$, VC, IC, ERV, IRV, and maximum phonation time. CONCLUSION: These results above show that aquatic breathing exercise training in water is more effective in improving the pulmonary function than general breathing exercise training.