Aim It is important to investigate the current prescription status and clinical outcomes of patients with schizophrenia receiving long‐acting antipsychotic injections. We aimed to determine the prescription proportion of long‐acting antipsychotic injections and hospital readmission proportions of patients with schizophrenia in Japan. Methods An open dataset was created using data from the National Database of Health Insurance Claims and Specific Health Checkups of Japan. Patient records with the term ‘schizophrenia’ were included. In Analysis 1, antipsychotic prescription proportions were determined for outpatients who had visited psychiatric facilities between 1 February 2015 and 31 March 2017. In Analysis 2, patients who had been discharged from a psychiatric facility and had received a long‐acting antipsychotic injection prescription within 90 days after initial discharge were selected; then, their readmission proportion was examined for 365 days after the initial discharge. Results The long‐acting antipsychotic injection prescription proportion was 3.5% for outpatients with schizophrenia receiving antipsychotics. The readmission proportion was 41.0% in the entire patient population, 36.2% in patients receiving typical long‐acting antipsychotic injections alone, and 23.5% in patients receiving atypical long‐acting antipsychotic injections alone. Conclusion Long‐acting antipsychotic injections are not yet widely used in Japan. The readmission proportion was lower in the patients receiving atypical than typical long‐acting antipsychotics injections. The results may provide important basic information to develop new future research questions but should be interpreted with caution because generalizability may be limited by the use of aggregated data and the data structure of the database used.