Tyrosine kinase inhibitors (TKI) are molecular targeted therapies that inhibit EGFR-related signal transduction pathway. Non-small cell lung cancer patients harbouring activating mutation benefit more from EGFR TKI in first line treatment than from standard platinum-based chemotherapy in terms of objective response rate, quality of life, progression free survival and, in some cases, overall survival. Treatment-related adverse events are observed in 70 per cent of patients but mainly in mild or moderate grade. The most common adverse events are: skin disorders, fatigue, diarrhoea, and elevated liver enzymes. Rare cases of interstitial lung disease are also observed. In clinical practice the treatment plan is achieved and drug discontinuation is rarely needed provided that the guidelines of prevention and management of the toxicities are followed.