This study investigated the irradiation pattern of muscles on the affected side in stroke patients after application of diagonal 2 extension (D2 ex) proprioceptive neuromuscular facilitation in the unaffected upper extremity. Seven stroke patients participated. Electromyographic activities were recorded in the iliopsoas, biceps brachii, and triceps brachii were recorded by surface electrodes at rest, D2 ex with knee extension, and D2 ex with knee 90 flexion, normalized by maximal voluntary isometric contraction (MVIC) values. The medial frequencies of biceps brachii in both sides were also measured to compare muscle type recruited. %MVIC of biceps brachii and triceps brachii were significantly higher in D2 ex than at rest (p<.05). There was no difference in median frequency of biceps brachii between the affected and unaffected side (p>.05). This suggests that proprioceptive neuromuscular facilitation using D2 ex may improve muscle activities of the paretic side and that the irritation pattern of the affected side may respond to maintain body equilibrium according to movement of the sound side.