The work is devoted to the analysis of the problems of occupational guidance of teenagers as the most important task of school education. The technology of a computer-network approach for determining professional preferences of schoolchildren and the possibilities of mastering preferred professions is considered. The hypothesis of the work is the suggestion of sufficient effectiveness of independent choice of the desired professions and the possibilities of their mastering on the basis of computer-network self-testing. 102 students of 9th grades of schools in St. Petersburg took part in this work, who successfully passed the self-testing in the computer program "Orientir", created on the basis of the famous test of A.E. Klimov. Preferred professions were found, that did not always correspond to the possibilities of their mastering. The maximum discrepancies were determined in the sector of professions "manman". Students least often chose the professions "mantechnology" and "man-nature". It was determined, that 20-25 % of schoolchildren are not able to choose a profession, using computer self-testing, they need psychological help to solve this problem.