OBJECTIVES:  The study objective was to evaluate the impact of initiation of long-acting injectable antipsychotics (LAI-AP) on health care resource utilization (HCRU) in different age groups of patients with schizophrenia. METHODS:  This study was performed using the Quebec (RAMQ) drug plan database. Patients with schizophrenia who were incident users of LAI-AP between January 2008 and March 2012, and with enrolment in the database during the study period were selected. HCRU and associated costs were analyzed during the year before and after LAI-AP initiation, using five age groups: <30, 30–39, 40–49, 50–59, and ≥60 years. RESULTS:  A total of 1,996 schizophrenia patients were included in the study and the average age was 43.4 years (SD=14.5). The average reduction of hospitalization days and total HCRU costs from the year before to the year after initiation of LAI-AP were 35.1 days (95%CI: 32.0-38.2) and $33,477 (95%CI: 30,347-36,607) respectively. Similar average reduction of hospitalization days and total HCRU costs were observed across all age groups. In the pre-initiation period, the costs associated with the total HCRU were on average higher among patients younger than 30 years ($69,915) compared to those aged 30 years and over ($54,529) (p≤0.01). CONCLUSIONS:  Initiation of LAI-AP in schizophrenia patients is associated with a significant reduction in HCRU, in all age groups. Also, in the year before initiation of LAI-AP, costs were higher in younger patients than in older patients. Further studies are required to estimate the long-term savings associated with early initiation of LAI-AP.