A limited controlled comparative study for the evaluation of the epidemiological efficacy of live recombinant and inactivated virion vaccines from A/Philippines/2/82-like strains of influenza A (H3N2) virus was carried out in schoolchildren of 8 to 15 years of age. During the influenza epidemic of 1987-1988 caused by influenza A/Sichuan/2/87 (H3N2)-like strains and by influenza B virus in 8.2-17% of cases, a statistically significant efficacy index for live influenza vaccine was 1.8 for the laboratory confirmed A (H3N2) cases. In the group vaccinated with the inactivated vaccine the number of serologically diagnosed A (H3N2) cases was 1.6 times lower than in the group receiving placebo, this difference being statistically significant. Thus, under the conditions of significant difference in the antigenic structure of the vaccine and epidemic A (H3N2) strains, both vaccines produced some diminished but statistically significant preventive effect in vaccinated children although its level was below the optimal. Revaccination of some children with a live influenza vaccine from a new A/Sichuan/2/87-like variant of A (H3N2) virus in the autumn of 1988 with reisolation of the vaccine strain also revealed the presence of some, though weak, resistance to this strain in the children vaccinated with both vaccines.