We report a case of aggressive angiomyxoma in ischiorectal fossa of a 39-year-old women. The tumor is characterized by relatively large size(13 x 11 cm), grossly gelatinous appearance and locally infiltrative nature. Microscopically, it consists of many variable sized blood vessels and spindle or stellate cells widely separated in myxoid or collagenous stroma. Immunohistochemical stains reveal that the tumor cells are strongly positive for actin and desmin. Electron microscopic findings are that of a few cells dispersed in abundant intercellular substance and collagen bundles. These cells form irregular cytoplasmic process without basal lamina and contain endoplasmic reticulum having cistern.