Treatment of aggressive pituitary tumors may be challenging. Temozolomide (TMZ) is a promising agent when conventional treatment methods fail. We present three patients with aggressive pituitary tumors with atypical morphology, who were resistant to conventional treatments and treated with TMZ. First case had a somatotroph adenoma, second a corticotroph adenoma, and the third a macroprolactinoma. We also reviewed the literature reporting TMZ efficacy in somatotroph, corticotroph and mammotroph tumors of pituitary. TMZ, 150–200 mg/m2 for 5 days in 28 days schedule was given to all patients. Among our patients, even though only the case of macroprolactinoma had a favorable response to TMZ treatment, both radiological and hormonal recurrences occurred 30 months after cessation of TMZ treatment. Then TMZ treatment was applied again. Cases of somatotroph and corticotroph adenomas had progressed under TMZ treatment and patients were lost due to mass effect of the tumor. Review of the literature demonstrated 67.3%, 60% and 26.7% overall response rates to the TMZ treatment in prolactinoma, corticotropinoma and somatostatinoma cases, respectively. There is still need to define response criteria uniformly to TMZ treatment in aggressive pituitary tumors and duration of response should be reported for reliable evaluation of results.