Schizophrenia (SCZ) is a severe chronic disease associated with significant functional impairments. Prior to a diagnosis of SCZ, some nonspecific symptoms may occur (i.e., anxiety, insomnia, depressive symptoms) and may progress into psychosis. While these may be attenuated or not of sufficient severity for psychosis, many will seek help for these symptoms. Understanding the predictors of SCZ remains a considerable challenge for clinicians. Thus, several studies have been conducted to explain the different premorbid trajectories of psychosis. Though, no consensus has been established on the prediagnostic characteristics of patients with SCZ and remains a matter of debate, especially for women and older patients. Hence, our study aims to clarify the psychiatric characteristics of patients from Quebec preceding their first episode of SCZ and address the influence of age and sex. To do so, we used administrative databases from the RAMQ (Physician billings) and MED-ÉCHO (hospital registry in Quebec) between January 1996 and December 2006; 98% of about 7.5 millions of inhabitants are registered with the universal health plan. It recorded 24,883 men and women over the age of 18 diagnosed with a first episode of SCZ between the years 2004 and 2007. Different psychiatric antecedents by groups of age and sex are reported by cumulative frequency. The sample comprised of 53% men. Approximately, 50% and 36% were diagnosed with SCZ by psychiatrists and family physicians respectively. Patients aged from 30 to 54 represented most of the sample; over half of men and women were first diagnosed after 30 years old. Those with no antecedents accounted for 65% of the sample, while overall 35% had at least one ICD-9 diagnosis, specifically and in descending order manic depressive psychosis, depressive disorder, and drug use disorder. In women under 30, anxiety, depressive disorder and adjustment disorder were more frequent. Whereas amongst men under 30, substance use disorder was the most common antecedent, followed by anxiety. Considering the total population coverage, these findings are interesting as they draw a representative global portrait of the population with SCZ before their diagnosis according to their age group and sex. This project recalls the importance of examining the first psychotic episodes to possibly intervene early in the course of the disease by addressing depressive disorders, anxiety disorders and substance use.