Objective To explore the effects of mental practice on upper extremity function after stroke. Methods Thirty sub-acute stroke patients were randomly divided into a treatment group ( n=15 ) and a control group (n=15). The patients in the control group were treated with conventional therapy. The patients in the treat-ment group were treated with motor imagery therapy in addition. All patients were assessed using the Fugl-Meyer mo-tor assessment (FMA) and the motor assessment scale (bIAS) before treatment and after 2, 4 and 8 weeks of treat-ment. Results After 2 weeks of treatment, average MAS scores in the treatment group improved significantly com-pared with before treatment, but there was no significant difference between the two groups. After 4 weeks, FMA and MAS scores in the two groups had improved, and the FMA scores in the treatment group were significantly higher than those of the control group. After 8 weeks, the FMA and MAS scores of both groups had further improved significant-ly, but the average FMA and MAS scores in the treatment group were now significantly higher than those in the control group. Conclusions Mental practice can improve the functional performance of the upper extremities of stroke pa-tients.