lonising radiation is known one of the most effective toots in the therapy of cancer but in many thoracic cancers, the total prescribed dose of radiation that can be safety administered to the target volume is limited by the risk of complications arising in the normal lung tissue. One of the major reasons for cellular injury after radiation is the formation of reactive oxygen species (ROS). Radiation pneumonitis is an acute phase side-effect which generally subsides after a few weeks and is followed by a chronic phase characterized by inflammation and fibrosis, that can develop months or years after irradiation. Carnosine is a dipeptide composed by the amino acids P-histidine and L-atanine. The exact biological role of carnosine is not totally understood, but several studies have demonstrated that it possesses strong and specific antioxidant properties, protects against radiation damage,and promotes wound heating. The antioxidant mechanism of carnosine is attributed to its chelating effect against metal ions, superoxide dismutase (SOD)-like activity, ROS and free radicals scavenging ability. Either its antioxidant or anti -inflammatuar properties, we propose that carnosine ameliorates irradiation-induced lung injury. Thus, supplementing cancer patients to whom applied radiation therapy with carnosine, may provide an alleviation of the symptoms due to radiation-induced lung injury. This issue warrants further studies. (c) 2005 Elsevier Ltd. All rights reserved.