The aim of this study was to determine from a health service perspective if the provision of rehabilitation to inpatients on a Saturday in addition to Monday to Friday was cost effective compared to Monday to Friday rehabilitation alone. Cost utility and cost effectiveness analyses were undertaken alongside a multi-center, single-blind randomized controlled trial with a 30-day follow up after discharge. Participants were adults admitted for inpatient rehabilitation in two publicly funded metropolitan rehabilitation facilities. The control group received usual care rehabilitation services from Monday to Friday and the intervention group received usual care plus an additional rehabilitation service on Saturday. Incremental cost utility ratio was reported as cost per quality adjusted life year (QALY) gained and an incremental cost effectiveness ratio (ICER) was reported as cost for a minimal clinically important difference (MCID) in functional independence. 996 patients (mean age 74 (standard deviation 13) years) were randomly assigned to the intervention (n = 496) or the control group (n = 500).