QUESTION: Is additional Saturday physiotherapy intervention beneficial for inpatients undergoing rehabilitation? DESIGN: Randomised controlled trial with concealed allocation, assessor blinding, and intention-to-treat analysis. PARTICIPANTS: Two hundred and sixty-two inpatients undergoing rehabilitation in an Australian metropolitan hospital. INTERVENTION: The experimental group received physiotherapy intervention from Monday to Saturday and the control group from Monday to Friday. OUTCOME MEASURES: Primary outcomes were hospital and physiotherapy length of stay. Secondary measures were collected to reflect patient outcomes (health state, independence, activity, flexibility and strength) and burden of care (discharge destination, adverse events, and follow-up physiotherapy intervention). RESULTS: There was a 3.2 day reduction for the experimental group (95% CI -0.5 to 6.9) in hospital length of stay and a 2.5 day reduction (95% CI -0.9 to 5.9) in physiotherapy length of stay. There was no significant between-group difference in change from admission to discharge for most of the secondary patient outcomes (health state, independence, activity, flexibility). The risk of the experimental group being categorised as strong relative to the control group was 1.2 (95% CI 0.99 to 1.50). The risk of not being discharged home, of having an adverse event, or requiring follow-up physiotherapy intervention was no greater for the experimental group than the control group. CONCLUSION: The provision of additional Saturday physiotherapy intervention resulted in a trend to shorter hospital and physiotherapy length of stay without affecting patient outcome unfavourably or increasing burden of care, suggesting that a larger multicentre trial is warranted.