The aim of this study was to evaluate discontinuation and hospitalization rates in patients with schizophrenia spectrum disorder who were treated with long-acting injectable (LAI) antipsychotics. We recorded clinical data about the period before the LAI treatment, when LAI treatment was initiated, and during the LAI treatment. Variables related to early (<8 weeks) and other LAI discontinuations and hospitalization were analyzed. Out of 452 patients, 14.4% of them discontinued their LAI treatment before 8 weeks, another 24.8% of the patients stopped their LAI by themselves later. Early discontinuers were younger, had shorter duration of illness, and less educated. Sixty-two (27.2%) of the patients were hospitalized under LAI treatment and 40% of the hospitalizations occurred in initial 6 months. Rate of hospitalization was 36.1% in the group who discontinued LAI after 8 weeks. In logistic regression analysis, younger age, history of combined antipsychotic treatment, number of hospitalizations before LAI, use of LAI for less than 6 months and alcohol abuse under LAI treatment were found related to hospitalization. Our findings suggested that discontinuation and hospitalization are still common among the patients who were treated with LAI antipsychotics.