[en] Our previous studies have demonstrated that an extract of Ganoderma lucidum occurring in South India possesses significant radioprotective property ex vivo. The present study describes the in vivo radioprotection of normal cells in tumour-bearing mice exposed to gamma radiation. Oral administration of G. lucidum extract (GLE) to tumour-bearing Swiss albino mice along with exposure to gamma radiation resulted in tumour regression. Single-cell gel electrophoresis (comet assay) on cells of normal and tumour tissues from tumour-bearing animals treated with GEE and radiation, revealed that there was significant reduction in radiation-induced damage to cellular DNA in normal tissues compared to the tumour, indicating preferential protection to normal tissues. The findings suggest the potential use of this mushroom extract as an adjuvant in radiotherapy, for tumour regression and prevention of radiation-induced cellular damages in normal tissues. (author)