Abstract Disclosure: R.D. Kennedy: None. M. Nicholson: None. Introduction: Giant pituitary adenomas, defined as pituitary adenomas measuring greater than 4 cm, present a therapeutic challenge because of their size, clinical features, and increased potential for complications following surgical intervention. Early detection and intervention to prevent growth and progression is paramount. We present a case of a patient with a giant 6.3 cm pituitary adenoma who had significant neurologic compromise, requiring surgical intervention, with resultant postoperative complications and death. Case:Patient is a 41 year old male with known history of pituitary adenoma who presented on 11/1/2023, from outside hospital, to the Neuroendocrine clinic with complaints of excessive truncal obesity, impotence, fatigue, and apathy. Vital signs were within normal limits. Physical exam revealed clouding of consciousness, grossly intact cranial nerve function, truncal obesity, and diminished power, tone, and bulk of the extremities. Formal visual field testing revealed bitemporal hemianopsia. A head CT scan revealed a 6.3 cm sellar mass with expansion of the sella, invasion of soft tissue into the sphenoid sinus, and extension of soft tissue cranially to the level of the third ventricle eccentric to the left. There was no evidence of apoplexy. Lab results revealed Prolactin of 924 ng/mL. The patient had been taking Bromocriptine, 2.5 mg daily, for at least three weeks. Less than three weeks after his initial evaluation, he returned to the hospital with complaint of acute ataxia. Pituitary MRI revealed 6.3 cm sellar mass with evidence of acute and subacute blood products, stretching of the optic chiasm from mass effect, extension into the bilateral cavernous sinuses, superior left MCA displacement, posterior left PCA displacement, 5 mm midline shift, uncal herniation and descending transtentorial herniation. The patient underwent endoscopic transsphenoidal resection with subsequent craniotomy for debulking. Postoperatively, he developed new right sided hemiplegia with aphasia with subsequent MRI finding of watershed infarct at the left MCA/PCA lateral posterior border zone territories with increasing mass effect over a 30 day hospital stay. He developed progressive global edema with worsening uncal and tonsillar herniations. Brain death was pronounced on 11/30/23. Discussion:This case highlights the importance of early intervention in patients with giant pituitary adenomas. Our patient had been experiencing right sided weakness for at least one year prior to his admission to our facility. In this case, earlier treatment with a dopamine agonist may have decreased the size of the adenoma or prevented rapid growth. This may have precluded the need for surgical intervention on an adenoma of this size, which carries increased risk for postoperative complications. Presentation: 6/2/2024