Radiation induced lung injury has long been considered a treatment limiting factor for patients requiringthoracic radiation. This radiation induced lung injury happens early as well as late. Radiation induced lung injurycan occur in two phases viz. early (< 6 months) when it is called radiation pneumonitis and late (>6 months) whenit is called radiation induced lung fibrosis. There are multiple factors that can be patient, disease or treatmentrelated that predict the incidence and severity of radiation pneumonitis. Radiation induced damage to the type Ipneumocytes is the triggering factor to initiate such reactions. Over the years, radiation therapy has witnessed aparadigm shift in radiation planning and delivery and successfully reduced the incidence of lung injury. Radiationpneumonitis is usually a diagnosis of exclusion. Steroids, ACE inhibitors and pentoxyphylline constitute thecornerstone of therapy. Radiation induced lung fibrosis is another challenging aspect. The pathophysiology ofradiation fibrosis includes continuing inflammation and microvascular changes due to pro-angiogenic and profibrogenicstimuli resembling those in adult bronchiectasis. General supportive management, mobilization ofairway secretions, anti-inflammatory therapy and management of acute exacerbations remains the treatmentoption. Radiation induced lung injury is an inevitable accompaniment of thoracic radiation.