The effects of recreational horseback riding therapy (HBRT) on gross motor function in children with cerebral palsy (CP: spastic diplegia, spastic quadriplegia, and spastic hemiplegia) were determined in a blinded study using the Gross Motor Function Measure (GMFM). Seventeen participants (nine females, eight males; mean age 9 years 10 months, SE 10 months) served as their own control. Their mean Gross Motor Function Classification System score was 2.7 (SD 0.4; range 1 to 5). HBRT was 1 hour per week for three riding sessions of 6 weeks per session (18 weeks). GMFM was determined every 6 weeks: pre-riding control period, onset of HBRT, every 6 weeks during HBRT for 18 weeks, and 6 weeks following HBRT. GMFM did not change during pre-riding control period. GMFM Total Score (Dimensions A–E) increased 7.6% (p<0.04) after 18 weeks, returning to control level 6 weeks following HBRT. GMFM Dimension E (Walking, Running, and Jumping) increased 8.7% after 12 weeks (p<0.02), 8.5% after 18 weeks (p<0.03), and remained elevated at 1.8% 6 weeks following HBRT (p<0.03). This suggests that HBRT may improve gross motor function in children with CP, which may reduce the degree of motor disability. Larger studies are needed to investigate this further, especially in children with more severe disabilities. Horseback riding should be considered for sports therapy in children with CP.