Objective : To describe trends, age, and sex-specific patterns of population hospital admissions with a diagnosis of craniosynostosis (CS) in Australia. Data Source : Population data for hospital separations (in-patient) from public and private hospitals (July 1996-June 2018) were obtained from the publicly available Australian Institute of Health and Welfare (AIHW) National Hospital Morbidity Database. Main outcome measures : The outcome variables were hospital separation rates (HSR) (number of hospital separations divided by the estimated resident population [ERP] per year) and average length of stay (aLOS) (patient days divided by the number of hospital separations) with a diagnosis of CS. Trends in HSR and aLOS adjusted for age, sex, and type of CS were investigated by negative binomial regression presented as annual percent change (APC). Results : In 8057 admissions identified, we observed no significant change in the annual trend for HSR for the 22-year period. However, a marginal annual decrease of 1.6% (95% CI: -0.7, -2.4) in the aLOS was identified for the same time period. HSR were higher for males, infants, and single suture synostosis. aLOS was 3.8 days (95% CI: 3.8, 3.9) per visit, longer for syndromic conditions. Conclusion : There was a minor reduction in the average length of hospital stay for CS over the 22-year period potentially indicative of improved care. Population-level information on hospitalisations for rare craniofacial conditions can inform research, clinical, and surgical practice. © 2022, American Cleft Palate-Craniofacial Association.