This study examined the effects of eccentric strength training on muscle function and functionality in football players with cerebral palsy (CP). Eight players (M=21.6, SD=5.9 years) performed bilateral lower limb (LL) eccentric strength training for six-week at 80% of one repetition maximum (ECC), three times per week, while nine players (M=20.9, SD=6.6 years) were used as controls (CTL). Knee extensor muscles isometric (MVC) strength, asymmetry between LL, thigh perimeter, balance (Y-balance test) and agility (Illinois agility test) were measured in both LL before and after training. CTL maintained all dependent variables unchanged after six weeks. MVC strength increased in the right (M=22.7, SD=9.6%; p<0.001; ES=1.12) and in the left LL (M=23.7, SD=7.6%; p<0.001; ES=0.93) after ECC. Strength asymmetry decreased (M=-22.7, SD=15.4%; p<0.001; ES=0.58) after ECC. Thigh perimeter increased in the left (M=4.8, SD=1.6%; p<0.001; ES=0.84) and in the right LL (M=4.4, SD=1.5%; p<0.001; ES=0.73) after ECC. Balance improved in the left (M=12.9, SD=3.2%; p<0.001; ES=0.84) and in the right LL (M=10.5, SD=4.5%; p<0.001; ES=0.63) after ECC. The results suggest that eccentric strength training seems to effectively increase muscle strength, balance, and thigh perimeter and decrease strength asymmetry in football players with CP.