Lymphocytic Hypophysitis (LH) is a rare and previously under-recognised disorder, most commonly affecting young females in the post-partum period. It presents clinically with symptoms and signs related to either a pituitary mass or hypopituitarism, frequently mimicking a pituitary adenoma; the diagnosis of LH can only be made histologically with the presence of a dense lymphocytic infiltration usually confined to the anterior pituitary. We present two case histories of patients who presented with symptoms suggestive of a functioning pituitary adenoma who also had concomitant LH confirmed histologically. The first case was a 39 year old lady, with a history of primary hypothyroidism, who presented with weight gain and hirsutism and clinical and biochemical features of Cushing's syndrome. The second case was a 61 year old male, also with a history of primary hypothyroidism, who presented with visual field loss and biochemically with hyperprolactinaemia. In both patients, magnetic resonance (MR) imaging of the pituitary demonstrated an enlarged partially cystic pituitary mass with slight suprasellar extension. Both patients were treated surgically with transphenoidal drainage and excision and histological examination of the surgical specimens demonstrated a mixture of pathologies with fragments of adenohypophyseal tissue (staining positive for ACTH and prolactin respectively) with a dense chronic inflammatory cell infiltrate suggestive of LH in nearby normal anterior pituitary. In both cases a joint diagnosis of a functioning pituitary adenoma with LH was made. There have been only several reported cases of this combination of pathologies but LH even in isolation is becoming increasingly recognised.