Among personnel in primary healthcare and psychiatric care, the ability to detect early signs of psychosis was examined and compared. Differences due to sex, age, profession or time in the profession were explored. Three different vignettes concerning patients with mental illness were presented to the respondents, and every respondent was to mark what they thought were early signs of psychosis in the vignettes. The findings were compared with a pre-set standard of symptoms and signs. Healthcare personnel from two different administrative districts, Umeå and Ornsköldsvik in northern Sweden, participated in the study. The response rate was 77%, but for district nurses in the administrative district of Umeå it was only 25%, so therefore complementary interviews with nine district nurses in that district, representing the drop-outs, were performed. There was no difference whatsoever in ability to detect early signs of psychosis between personnel in primary healthcare and psychiatric care; nor were there any significant differences due to sex, age, profession or time in their profession. Detecting early signs of psychosis requires training and the ability to communicate with patients, as well as a special sensitivity to psychiatric conditions. This can be achieved by enhancing accessibility and continuity of primary healthcare for these patients. Furthermore, a greater sensitivity to early signs of psychosis must be created among all healthcare personnel. The co-operation between primary healthcare and psychiatric care must increase. Primary care physicians need opportunities to see patients over time in order to correctly interpret early signs and symptoms of psychiatric illness.