Objective: To investigate the effects of two weeks of intensive mass practice with a constraint-induced movement therapy approach for the lower extremity in five chronic poststroke patients, and the persistence of effects at three and six months. Design: A single-subject experimental design (SSED) was used with an AB design and follow-ups three and six months later. Setting: Outpatient rehabilitation at Torsby Hospital in Sweden. Main measures: Motor function in lower extremity, mobility, dynamic balance, weight-bearing symmetry and walking ability were measured on six occasions during two weeks (A phase), with the Fugl-Meyer assessment for lower extremity, the Timed Up and Go, the Step Test, the Timed Walking Test and the Six-Minute Walk Test. During the intervention's B phase, six measurements were performed with the same time intervals as in the A phase. There were follow-ups three and six months later. Intervention: The intervention (B phase) consisted of bicycling, training in water, strength training, standing weight-bearing, walking up and down stairs, walking indoors and outdoors and flexibility training of the lower extremity, on all weekdays, 6 h a day for two weeks. Results: The results showed improvements in 23/30 variables (77%), 12 of them statistically significant (52%). At follow-up, 22/23 improvements persisted. For example, three of five subjects walked significantly further after the intervention and the follow-ups showed that they still walked further than before the intervention. Conclusion: Intensive mass practice with constraint-induced movement therapy for the lower extremity can improve motor function, mobility, dynamic balance, weight-bearing symmetry and walking ability in chronic poststroke patients.Long-term follow-up showed that the effects persisted for these five subjects.