This study examined cost drivers of 2,490 completed episodes of ambulatory physiotherapy care provided over an eight-month period in seven public hospitals in three Australian states. An episode described the physiotherapy outpatient management for a particular patient with a particular condition, and consisted of start and finish dates, and all the occasions of service in between. The most robust description of a physiotherapy episode of care was unit record attributable time, split at 120 minutes. Factors which were strongly associated with physiotherapy episodes were age, referral mechanism, source of income, chronicity, country of origin and travel arrangements. This study highlights areas which require attention before further large scale studies can be conducted, and provides a basis for future investigations into the cost of providing physiotherapy ambulatory services.