Malignant pleural effusion is a very common entity in our environment, given the high number of patients with neoplastic disease who present a terminal condition of their underlying disease. The chemical pleurodesis with iodine is a useful, safe and effective tool in its treatment and has been performed at the Hospital Universitario Mayor. It is because of the above that it is essential to know the factors associated with the results unfavorable to this procedure with the aim of giving a better management of these patients