Aim: We aimed to characterize youth hospitalization trends in a psychiatric inpatient unit from a large, public university hospital with a broad catchment area in Milan, Italy. Methods: Hospitalization data of patients with an age at admission ≤ 35 were retrospectively retrieved over a time span of 15 years. The sample was comprised of 1982 admissions to a psychiatric ward, aggregated into ICD-10 diagnostic clusters and then analysed. We investigated the epidemiological trends with a focus on age at admission, gender, nationality and hospitalization rates, length of stay and "revolving door" readmissions within a year. Results: Hospitalization rates increased for eating Disorders and decreased for nonaffective psychotic disorders; median length of stay generally decreased; hospitalization rates for foreign youth increased, in particular for those diagnosed with nonaffective psychotic disorders, personality disorders, and substance-related and addictive disorders. The revolving door phenomenon was also associated with nonaffective psychoses and neurodevelopmental disorders, while found to increase for eating disorders. Conclusions: Hospitalization patterns reflect the general increase of foreign youth in the suburban tissue of a large metropolitan area like Milan. However, our data might underestimate the constant growth of mental health problems in foreign youth due to a generally lower access to services. Novel pharmacological treatments and early intervention programs might explain the decrease of hospitalization duration and hospitalization rate for youth with non-affective psychoses. The observed increase in hospitalization for young patients with eating disorders sustains the development of adequate policies tailored towards specialty wards. K E Y W O R D S hospitalization trends, psychiatric services, psychosis, revolving door, youth inpatient care 1 | INTRODUCTION Most findings associated with the course of psychiatric disorders suggest that early identification and treatment leads to improved outcome (Brimblecombe et al., 2017). The clinical relevance of early intervention programs has gained increasing attention over the past few decades, in full agreement with current understanding of primary and secondary prevention in psychiatric disorders. Prospective patients' awareness of mental health and associated problems is influenced by several features that shape their access to mental health