Published data indicate that an inverse correlation has been identified in some tumours such as ovarian cancer and laryngeal squamous carcinoma. This study aimed to characterize alteration in the immunohistochemical expression of p16 and pRb in carcinoma ex pleomorphic adenoma, and to assess the inverse correlation between p16 and pRb in carcinoma ex pleomorphic adenoma. A selected series of 27 cases of carcinoma ex pleomorphic adenomas were examined at Alfarabi Dental School in 2012. The results showed an inverse correlation between p16 (normal expression) and pRb (mutated) in 15 cases. Also 3 cases showed an inverse correlation between p16 (mutated) and pRb (normal expression). p16 and pRb (both proteins with normal expression) were identified in 3 cases. p16 and pRb (both proteins inactivated) were identified in 6 cases. This study suggests the alteration of p16 and pRb expression has been detected in carcinoma ex pleomorphic adenomas. They mentioned that if the function of one gene such as p16 or pRb was abrogated the other gene would be overexpressed or unaffected in 18 out of 27 cases.