To apply rehabilitation program for stroke patients' functional improvement, various factors such as timing for initiation of rehabilitation, intensity of therapy, and individual compliances should be considered. Both animal and neuroimaging studies suggested that greater intensity of therapy is associated with increased cortical reorganization and subsequent functional recovery, and repetition also may play a major role in inducing and maintaining brain plasticity. However, the proper intensity of rehabilitation therapy has not been well established yet. In this review, we examined the previous studies assessing the effect of intensity and repetition of therapy on functional recovery. From the randomized controlled trials and meta-analysis, increased intensities of treatment and repetitions are shown to be effective in improving activities of daily living and gait function, but limited evidences in functional outcomes of upper extremities. It is difficult to provide standardized optimal intensities and repetitions in clinical practice because of the variability in components of rehabilitation therapies, patients' motivation and participation, the degree of therapists' involvement, and reimbursement and healthcare system. Clinical practice guidelines of US, Europe and Korea recommended that intensive rehabilitation and repetitive task training should be provided to post stroke patients in rehabilitation unit. Further studies are needed to investigate the effective delivery system of rehabilitation program in terms of repetition and intensity.