Background: Background: Cypermethrin (CYP) is a synthetic pyrethroid used as a pesticide. It induces toxicity of different organs. Hydroxytyrosol (HT) can protect against oxidant-induced toxicity and promote programmed apoptosis counteracting cellular infiltration. Aim: The present study aimed to assess the CYP-induced histological, immunohistochemical and biochemical changes in rat lungs and to clarify the protective role of HT. Materials and Methods: Forty adult male albino rats, their wights were (150–200 g), were used. The rats were equally distributed into four groups as follows; control group gavaged by oral route with corn oil (1 ml/kg/day), HT group gavaged by oral route with HT (50 mg/kg/day dissolved in I ml distilled water), CYP-treated group gavaged by oral route with CYP (20 mg/kg/day dissolved in I ml corn oil), and CYP+HT treated group treated orally with CYP and HT (as previous doses) for 14 days. All groups underwent histological lung examination, immunohistochemical, morphometric and biochemical analysis. Results: This study showed that CYP caused a significant rise in MDA with a significant decline of SOD, CAT, and GSH levels. Histological changes revealed extensive cellular infiltration, thickening alveolar septum, increased angiogenesis with areas of hemorrhage, extravasation of blood, and decreased areas of ventilation in lungs of rats treated with CYP. Moreover, ultrastructural observations confirmed previous results. A noticeable improvement of the affected lung tissues was observed with HT treatment in the form of regaining of normal epithelial bronchial lining, re-inflation of alveoli and nearly intact intima of the blood vessels as well as restoration of type II pneumocyte structure. Conclusion: HT was proved to ameliorate the CYP-induced histological, immunohistochemical and biochemical changes in rat lung. This could be explained by HT's anti-inflammatory and antioxidant properties and scavenging abilities against active free radicals. These findings can be of value for future clinical applications.