The purpose of this study was to quantify long-toss throwing mechanics of professional baseball pitchers and compare biomechanics of mound pitching to long-toss throwing. Kinematic and kinetic data from 19 professional baseball pitchers throwing from 18-m to 91-m, along with fastball pitches were analyzed using marker-based motion analysis and linear mixed models. Throwing approach and arc were not restricted for long-toss throws. Linear associations were found between the long-toss throwing distances and biomechanical metrics. While elbow and shoulder kinetics increased with distance, they were lower than pitching kinetics at shorter distances and did not significantly exceed the average pitching kinetics at the maximum distance. This is the first study to quantify long-toss throwing mechanics without restriction of throwing style