To analyse the trend in ambulatory surgery procedures in Catalonia (Spain) hospitals with regard to the activity in inpatient care units and structural resources in surgery.A descriptive study was performed using data from the Statistics of Health Facilities with Inpatient Care of the Health Department of the Catalan Government from 2001 to 2011. Data from acute care hospitals were analysed and were classified in public and private hospitals.The percentage of ambulatory surgical procedures increased by 63.2% and the percentage of inpatient surgery decreased by 23.5% (this trend was more pronounced in public hospitals). This result coincided with a decrease of structural resources in surgery (beds and operating rooms) and with an improvement in inpatient surgical activity (a decrease in the mean length of stay and bed occupancy rate in all hospitals). Structural surgery resources were optimized and efficiency was improved in surgery inpatient care units.