The aims of the study were: (1) to determine the feasibility of a rehabilitation program combining intensive therapy periods (4 times/week for 4 weeks) with periods without therapy (8 weeks) over a 6-month period in severely impaired children with cerebral palsy (CP); and (2) to measure changes in gross motor function after intensive therapy periods (immediate effects) and rest periods (retention). A convenient sample included five children (two females, three males; mean age 22.6 months [SD 9.9]) with severe forms of CP with impairment of four limbs and trunk (GMFCS levels IV and V). A multiple-baseline design was used. Changes in motor performance were assessed by a blind evaluator using the Gross Motor Function Measure. Visual and statistical analyses followed. Level of compliance during intensive therapy was 93.1%. Children received a mean of 30 treatments over the 24 weeks of the experimental phase compared with the 48 treatments they would have received routinely. Increases in GMFM scores (mean 9.2%; range 3 to 15%) were significant in three children (p<0.05) and all participants maintained their motor performance during the two 8-week rest periods. Results showed that four treatments per week over a 4-week period were well tolerated when separated by rest periods. The intermittent program led to improvements in motor function that were maintained over the rest periods. Results underline the need to reconsider the organization of physical rehabilitation programs. A regime that is intensive enough without being tiring and one that provides practice conditions for consolidating motor skills learned during the intensive therapy period may best optimize motor training.