In this study, the authors compared the k-Nearest Neighbor (k-NN), Quadratic Discriminant Analysis (QDA), and Linear Discriminant Analysis (LDA) algorithms for the classification of wrist-motion directions such as up, down, right, left, and the rest state. The forearm EMG signals for those motions were collected using a two-channel electromyogram(EMG) system. Thirty normal volunteers participated in this study. Thirty features with a time-window size of 166 ms per feature during a 5-s forearm muscle motion were extracted from the gathered EMG signals. The difference absolute mean value (DAMV) was used to construct a feature map and the LDA, QDA, and k-NN algorithms were used to classify the directions of the signal. The recognition rates were 84.9% for k-NN, 82.4% for QDA, and 81.1% for LDA. There was a statistically significant difference between the k-NN and LDA algorithms (P < 0.05). Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.