Monitoring of radon in underground mines is important in order to assess the radiological hazards to occupational workers. Radon concentration levels in three underground lignite mines (Tunçbilek, Ömerler and Eynez) of Turkey were obtained in this study. For this reason, atmospheric radon level measurements were carried out in mines using CR-39 track detectors. Chemical etching of the detector tracks and subsequent counting were performed at Çekmece Nuclear Research and Training Center. The obtained results were evaluated according to the International Commission of Radiation Protection and the Turkish Atomic Energy Authority whose radon action levels for workplaces are 500-1500 and 1000 Bq. -3, respectively. The radon gas concentrations in the lignite mines were determined to be between 50 ± 7 and 587 ± 16 Bq m. -3. The results obtained in these experiments are far under the action levels. The computed radon doses for the mine workers of Tunçbilek, Ömerler and Eynez lignite mines are 1.23, 2.44 and 1.47 mSv y. -1, respectively. © The Author 2009. Published by Oxford University Press.