Power frequency magnetic fields have unfavourable impacts on human health, especially on children who are growing up. The aim of the present study was to carry out an electromagnetic field measurement and evaluate the impact of transformers, high voltage powerlines, municipal electric distribution lines. A cross-sectional study was conducted in which the power frequency magnetic field levels were determined at 45 primary schools in Yenimahalle district, Ankara. The measurements were taken by using a gaussmeter at specific points of school buildings and gardens. Whether there were any transformer, high voltage powerline, municipal electric distribution line was searched for and if there were, their distances were measured. Data obtained from the study was analysed using SPSS 10.0 program. It was determined that there were high voltage powerlines near 15 of the schools, transformers near 22 of them, municipal electric distribution lines near 30 of them and base stations near 17 of them. As a result of measurements taken, the average values were found as 2.65 +/- 4.11 mG in the gardens and 0.3 +/- 1.16 mG in the buildings. At 51.1% of the schools (23 schools), average magnetic field level was lower than 1 mG, and at 26.7% of the schools (12 schools) it was more than 2 mG. The general average for all of the values that were measured at schools was 1.65 +/- 1.74 mG. It was determined that transformers and high voltage powerlines could be a source of electromagnetic radiation at schools.