Forty tournament-level tennis players with expert serve technique volunteered to have their serve evaluated to determine relationships between anthropometric data, extremity strength, and functional serve velocity. All players underwent a complete physical examination, a video taped serve analysis, a radar measurement of serve velocity, and a series of upper extremity strength measurements. Statistical analysis was performed to determine which factors were related to serve velocity. Statistically significant relationships were found between serve velocity and several flexibility measurements including increased dominant wrist flexion (P < 0.05), increased dominant shoulder flexion (P < 0.05), and increased dominant shoulder internal rotation at 0 degrees of abduction (P < 0.05). Several strength measurements were also related to serve velocity including elbow extension torque production (P < 0.01) and the ratios of internal to external rotational torque production for both low- and high-speed measurements (P < 0.01 concentrically and P < 0.05 eccentrically). These findings relate strength and flexibility to serve velocity, suggesting that it may be possible to increase a tennis player's serve velocity through specifically directed muscular strengthening or stretching regimens. However, prospective studies must be undertaken to demonstrate these possibilities.