Lead-alkali-silicate glass samples were irradiated with 0.998-35.939 kGy dose levels using a Co-60 gamma radioisotope source. The colour of the lead-alkali-silicate glass turned to brownish orange with absorbed dose. Radiation-induced changes in the properties of visible light transmittance and absorbance were examined between wavelengths of 380 and 1500 nm using a spectrophotometer. Changes in the optical colour parameters were determined and compared with those of unexposed glasses and it is shown that they can be used as radiation dosimeters, especially for medical dosimeters. (C) 2001 Elsevier Science Ltd. All rights reserved.