The movement dynamics and physical profile specifically related to handling a wheelchair, such as starting, sprinting, braking, turning and blocking are crucial to wheelchair basketball (WCB) performance. The movement dynamics and physical profile for WCB players are dependent on fundamental factors such as muscle strength and range of motion (ROM) of the upper extremity, the reaction time, and the upper-body segment length. The purpose of this study was to determine the contributions of the selected fundamental factors (arm length, sitting height, simple reaction time (SRT) and choice reaction time (CRT), muscle strengths and ROMs at the shoulder, elbow, and wrist joints) to the WCB performance (average points, rebounds, assists, blocks and steals per-game in the season statistics, and the coaches' evaluations) for Paralympic WCB players. Thirty-seven Paralympic WCB players (mean age: 28.75+7.52 years, mean body mass: 58.93+12.24 kg, and mean time of playing-WCB: 9.75+6.68 years) from seven countries participated in this study. A self-developed computerized reaction time system was used to test the SRT and CRT. The ROMs and the muscle strengths at the shoulder, elbow, and wrist joints were measured by a plastic goniometer and a MP DA100B BioPac force measurement system, respectively. Stepwise regression analysis was used to identify the contributions of these fundamental factors, and the "dimensional variables" (DV) derived from the fundamental factors to the WCB performance. A DV represented a dimension or category of the factors, such as the wrist flexion/extension ROM DV represented the ROM of the wrist flexion and extension, and the WCB performance DV represented the average points, rebounds, assists, blocks and steals per-game. The results of this study indicated that the elbow extension ROM and the wrist extension ROM had significant (p<0.01) contributions to the average points per-game; the sitting height, the shoulder internal rotation ROM and the elbow flexion ROM had significant (p<0.001) contributions to the average rebounds per-game; the arm length had significant (p<0.05) contribution to the average assists per-game; and the elbow flexion ROM and the SRT had significant (p<0.01) contributions to the average blocks per-game. The regression model of DV indicated the wrist flexion/extension ROM DV and the wrist flexion/extension strength DV had significant (p<0.01) contributions to the WCB performance DV. It is concluded that the ROMs of the shoulder internal rotation, elbow extension, wrist flexion/extension, and the CRT, and the wrist flexion/extension muscle strength are crucial to WCB performance and should be addressed in WCB training.