Adenoviruses are a group of viruses that can infect the membranes (tissue linings) of the respiratory tract, eyes, intestines, and urinary tract. Localization of adenovirus occurs in the superficial epithelium/mucosa and adenovirus must be differentiated from CMV and HSV, which have similar overlapping morphological features. Adenovirus infection is associated with a broad spectrum of clinical disease in both children and adults. It has gained more attention as an important complication in patients who have undergone bone marrow or solid organ transplantation. The incidence of adenovirus infection in bone marrow transplant patients has been reported at 5-20%. Adenovirus infection on morphology should be differentially diagnosed from other virus infections, especially CMV infection. Anti-adenovirus can assist in this differential diagnosis by showing a round or crescent-shaped nuclear inclusion, generally within the surface epithelium and is exclusively intra-nuclear in location.