Introduction: Teratomas are neoplasms which have their origin from one or usually all three germ cell layers, i.e., ectoderm, mesoderm, and endoderm. Most common sites involved are gonads. Other common extra-gonadal sites are mediastinal, sacro-coccygeal and pineal regions. Among the retroperitoneal teratomas, primary adrenal teratomas are very rare with an incidence rate of 0.13%. Here, we report a case of large adrenal teratoma which was misdiagnosed radiologically as adrenal myelolipoma.Case Presentation: A 40-year-old female presented to Endocrinology out-patient services with left hypochondriac pain for the last one year. Her clinical examination was normal. Contrast-enhanced computed tomography of abdomen revealed a left sided large adrenal mass measuring 11.2 x 10 x 10 cm showing fat attenuating lesion with enhancing soft tissue component, internal septation, and coarse calcifications and was reported as adrenal myelolipoma by the radiologist. However, the review by Endocrinologist lead to suspicion of adrenal teratoma as the areas of calcification, in fact, had typical bone formation with cortex and medullary components. Patient underwent left adrenalectomy. Histopathological examination confirmed the lesion as mature cystic teratoma with microscopic foci of papillary carcinoma of thyroid and neuro endocrine tumour.Conclusion: Even though adrenal teratomas are usually benign, malignant transformation may occur. Hence, it is important to make a proper diagnosis of the condition for appropriate management. Imaging characteristics of medullary component in the calcification areas should suggest the possibility of adrenal teratoma over other adrenal lesions with calcifications.