The origins of the secondary school system in Czechoslovak territory date from the 1850’s. A partial reforms of this system was carried out in 1933, whereby the lower forms the three types of grammar school (classical, technical and comprehensive) were brought closer together. In 1948 the higher forms of all types of grammar schools formed a single type of a new, four-year grammar school, whereas their lower forms were merged with the secondary modern school to form a unified type of basic school. In 1953 the basic school was joined to the existing grammar school to form the eleven-year school, which consisted of eight years of basic school and the last three years were selective, replacing the former four year grammar school. The Education Act of 1960 provided for compulsory attendance of nine years at the basic nine-year school and the last three forms of the eleven-year school were turned into a secondary general school. In 1965 the secondary general school was differentiated into two sides — science and arts. In addition to day schools there is an extensive network of secondary schools for working people. Each change in the organization of secondary education brought with it changes in the curricula and a substantial part of the article deals with their comparison. The author points out that the shortening of the secondary school from four years to three had unfavourable consequences especially in the teaching of languages (Latin was dropped and the teaching of Modern languages was restricted) and of social sciences. On the other hand the leaching of physics and chemistry was reinforced In comparison with the former state. The ’’fundamentals of production“, which was newly introduced as a subject in 1961, had a great number of teaching periods because the secondary school was to prepare its pupils for simple manual occupations. But this diverted the secondary school from its main purpose, i. e. preparation for study at universities. Consequently the number of teaching periods devoted to fundamentals of production was cut and that of some other subjects was extended. In 1965 Latin was re-introduced at the secondary general school (in the arts side as a compulsory subject, in the science side as an optional one), the teaching of modern foreign languages was reinforced; both sides give instruction in psychology, logic and philosophy, the science side has extended the teaching of mathematics and natural sciences. All the curricula since 1948 have stressed education and instruction in the spirit of Marxism- Leninism and the scientific world, outlook. What is a great asset is the democratization of education. The secondary general school now has nearly four times as many school-leavers as it had before 1938. Whereas before 1938 only a very small number of children from working class families attended the grammar schools, nowadays 41 per cent of secondary school pupils are of working-class origin and a great many workers study at the secondary school as part-time students while they work. And thus in spite of certain shortcomings resulting chiefly from the reduction of secondary education to three years, after the changes in 1965 and 1966, does mean a step forward.