Background Baseball throwing is typically done with one dominant arm and after years of throwing the skills becomes autonomous and improvement is slowed. Incorporating training of the non-dominant arm could induce a cross-education effect and assist in improving the dominant throwing arm. Therefore, the purpose of this study was to determine the effect of contralateral (CL) throwing practice on dominant arm throwing accuracy and other parameters in experienced baseball players. Methods 16 male high school baseball players participated in contralateral throwing practice. Each participant was randomly assigned to either contralateral (CL) or control (CON) following a pre-test. Sessions consisted of 30 non-dominant arm throws from a randomized location to a standard catch net, twice a week for 4 weeks. Following the 4 weeks of training, participants were post-tested to determine the effects of the contralateral throwing program. Accuracy percentage, throwing velocity, Accuracy:Velocity ratio, and non-specific throwing parameters were collected to determine the effect of the contralateral throwing program. Results For dominant side throwing accuracy %, significant pre- to post-testing differences were demonstrated in the CL condition (p < 0.05, Pre = 47.4, Post = 54.9). Accuracy:Velocity ratio was statistically significant in the CL condition in pre- to post-test (p < 0.05, Pre = 0.71, Post = 0.86). There were no significant differences detected in non-throwing specific parameters. Conclusion Contralateral throwing practice improved accuracy and Accuracy:Velocity ratio in the dominant arm of the CL group. Use of a contralateral throwing program can be used to improve performance in a well learned, complex, open skill such as baseball throwing.