Mango malformation disease (MMD) is an economically important disease of Mangifera indica globally. Fusarium subglutinans has been associated with mango floral and vegetative malformation although confusion still remains regarding the etiology of the disease. In order to determine the Fusarium subglutinans penetration site, artificial inoculation of mango seedlings variety Alfonso were conducted. When soil was infested with F. subglutinans, the malformation was detected in the buds, three months post inoculation. Symptoms of the disease include loss of the apical dominance and swelling of vegetative buds, proliferation of leaves and flowers, phyllody and hypertrophy of panicle axes. Using scanning electron microscope (SEM), symptoms of vegetative and floral malformation appeared where mycelium of Fusarium subglutinans were present in the tissue at high concentrations compared to that of the untreated controls. Studies also revealed the presence of, pin-sized to large holes, disorganised cells and fungal mycelial infection at the base of the malformed buds during bud-inception stages. Moreover, Fusarium isolate colonized seedling root systems and became systemic, spreading to above-ground plant tissues include apical and lateral buds. Fusarium subglutinans proved to be the dominant fungus. [Nature and Science. 2010;8(4):122-127]. (ISSN: 1545-0740). Key words: Egypt, F. subglutinans, Mango Malformation, Mangifera indica.