ENExperiment of coordinated teaching of biology and chemistry was started in two schools of Vilnius (Vilnius Lyceum of Sciences and Maths, M. Birjiökos Gymnasium) in 1997. Two more schools joined the experiment later: Gabijos Gymnasium (Vilnius), Varpo Gymnasium (Kaunas). 185 students are taking part in the experiment in 1999/2000 school year. In our experiment general and inorganic chemistry is covered during the 9 year instead of the period of 9-10 years. 10-11 years cover the course of organic chemistry, which is considerably expanded with chapters on natural compounds. Curricula of biology and chemistry are coordinated in such a way, that chemical information needed for modem biology teaching is given before it will be used in biology teaching. Opposite situation exists in the present school curricula: chapters on carbohydrates, proteins and nucleic acids are studied at the end of the 11 year chemistry course after cell biology and genetics has been studied according to the curricula of biology.