The thymus is an encapsulated soft bilobed organ lies in the superior mediastinum and anterior part of the inferior mediastinum. Presence of Enlarged thymus in adult is not so common because thymus size and parenchyma gradually atrophies after puberty finally replaced by fibro fatty mass. Objectives: To Study the Histo morphology of the bilobed enlarged thymus in adult human cadaver. Materials and Methods: Collected persistent enlarged thymus in adult human cadaver then performed histological staining to study the parenchyma. Conclusion: we discussed morphological and histological facts about the present study. This study is clinically important for radiologists to make a differential diagnosis in case of a mediastinal mass.