Although adrenal tumors detected during pregnancy are extraordinarily rare, the pathophysiologic repercussions of untreated adrenal neoplasms are enormous to both mother and fetus. From our computer-based registry of pregnant patients from 1975 through 1996 (n = 30,246), four cases of adrenal neoplasms associated with pregnancy were identified (0.013%), analyzed, and compared with the current medical literature. Four women ages 36, 29, 22, and 21 years had adrenal neoplasms diagnosed with pregnancy. Patient 1 had an unsuspected pheochromocytoma identified at autopsy. At 27 weeks into her pregnancy the patient suffered a myocardial infarction, and both she and the fetus died. Patient 2 was incidentally found to have adrenal and pancreatic neoplasms on screening abdominal computed tomography for von Hippel-Lindau disease. The study identified a pregnancy. She elected to terminate the pregnancy and underwent resection of both tumors. She died 3 years later of metastatic islet cell cancer. Both of these patients had previously delivered healthy babies, but both pregnancies were complicated by hypertension. Patient 3 had a functional adrenal tumor identified initially by urinary aldosterone studies because of symptoms of severe hypertension, and patient 4 had an adrenal mass diagnosed via ultrasonography at 30 weeks' gestation because of concerns for right-sided pyelonephritis. These two women underwent careful monitoring throughout the remainder of their pregnancies with eventual delivery of healthy babies. Both women later underwent successful operative resection of benign adrenal adenomas. Adrenal neoplasms discovered during pregnancy are rare. The onus, however, is on physicians to consider this diagnosis in pregnant women with hypertension, headaches, or other manifestations of adrenal disorders. Surgical management of identified adrenal lesions is thereafter straightforward. Missing the diagnosis has grave implications for these young women and their fetuses.