Background:Living in urban environment represents a well-known risk factor for the development of mental disorders. Here we aimed to investigate whether urbanicity has also an effect on the trajectories of psychiatric disorders. For this purpose, we analyzed the relationship between urbanization and hospital readmission risk. Method:We analysed the impact of geospatial, demographic, clinical and socioeconomic data on hospital readmission risk in a sample of 17’145 patients observed during a 12 years period starting from 1996 and leading to 37’697 psychiatric hospitalizations by using a frailty model Results:Living in more urbanized regions was related to an increasing risk for earlier rehospitalization. The impact of urbanicity was less pronounced in patients with affective disorders and more pronounced in patients with co-morbid substance abuse disorder. Shorter distance to the hospital and change of residence increased the readmission risk. Population density, proportion of non-german citizens, local population growth tendency, and local unemployment rate were not associated with readmission risk. Conclusion:A clear impact of urban living environment on the course of mental disorders was demonstrated. In metropolitan regions of our sample it took one year till 50% of discharged patients had been readmitted to the psychiatric clinic, whereas this took 6 years in rural regions.