Most previous studies of electromyography (EMG) pattern recognition control of multifunctional myoelectric prostheses adopted a conventional sampling rate that is commonly used in EMG research fields. However, it is unknown whether using a lower sampling rate in EMG acquisition still preserves sufficient neural control information for accurate classification of user movement intents. This study investigated the effects of EMG sampling rate on the performance of EMG pattern recognition in identifying 11 classes of arm and hand movements. Our results showed that decreasing the sampling rate from 1 kHz to 500 Hz only caused 0.8% reduction of the average classification accuracy over five able-bodied subjects and 2.2% decrease over two transradial amputees. When using a 400 Hz sampling rate, the average classification accuracy decreased 1.3% and 2.8% in able-bodied subjects and amputees, respectively. These results suggest that a sampling rate between 400-500 Hz would be optimal for EMG acquisition in EMG pattern recognition based control of a multifunctional prosthesis.