The measurements of radon concentration in 58 buildings of day nursery schools and kindergartens were performed in the six province of the East North Poland. The measurements of indoor radon were performed by means of a charcoal canister (Pico-Rad). The concentration ranged from 4.5 to 320 Bq/m3 and have arthimetic average 24.5 Bq/m3, geometric average 15.7 Bq/m3, median 15 Bq/m3. The highest average values were observed in Suwałki Province and Olsztyn Province. The results of all these measurements do not exceeded the limit of the Polish law.