The objective of this study was to determine the success of intervention that was designed in order to change attitudes of high school students toward seeking professional psychological help. The gender and type of school that participants are attending were taken into consideration. The sample consists of 379 high school students in Zagreb, of whom 192 are attending vocational school and 187 are attending gymnasium. Out of total number of participants, 192 listed their gender, of whom 62 are male and 130 are famale. All participants were given the Inventory of Attitudes Toward Seeking Mental Health Services (Mackenzie, Knox, Gekoski i Macaulay, 2004). Before filling out the inventory, only the participants of the experimental group were given a short text that confutes some of the prevalent prejudice and negative stereotypes about psychological interventions and people who are seeking psychological help. The results of the research show that intervention made participants more inclined to seek psychological help and psychologically more open. Furthermore, the results show that girls are significantly more inclined to seek psychological help, more indifferent to stigma and more psychologically open than boys. Analysis of variance has shown that there is no statistically significant difference between students who are attending vocational school and students who are attending gymnasium in terms of help-seeking propensity, psychological openness and indifference to stigma. Intervention has been shown to be more effective in changing the boys' attitude toward seeking psychological than girls'. Intervention made difference only in terms of greater indifference to stigma. The intervention also proved to be more effective in changing attitude of students who are attending gymnasium compared to students who are attending vocational school. Intervention made difference in terms of greater indifference to stigma and greater help-seeking propensity. :