This investigation was planned to study the histopathological changes caused by Trichophyton rubrum and study the therapeutic activity of Fumaria officinalis (ethanolic extract) on the infected skin by using light microscope (in vitro and in vivo). Clinical features of animal skin infected with Trichophyton rubrum was represented by scaly area with alopecia, irregular margin with papule, boil formation, redness, swelling, ulceration and loss of hair. Light microscopic studies have shown certain degenerative changes in the infected area these changes were represented by oedema with heavy acute inflammatory cell in dermis area extended to hypodermis, abscess formation and congestion of blood vessels. Clinical features pf animals skin infected with Trichophyton rubrum and treated with Fumaria officinalis extract represented that crust tend to drop-off spontaneously after the five day, leaving white scar, usually slightly depressed along it’s entire length. Healing after eleventh day of the treatment with Fumaria officinalis extract the incision was completely covered with newly formed epithelium and the hair seen in comparism with fugnidin ointment with which healing was represented by slower regenerative changes, crust tend to drop-off spontaneously and the incision which covered the area were less than those covered the area treated with Fumaria extract, indicating the efficiency of Fumaria ethanolic extract as antifungal agent. Light microscopic studies revealed certain regenerative changes in the infected area after the treatment with Fumaria officinalis extract, these changes were represented by more moderate inflammatory reaction with accumulation of neotrophile and monocyte in the epidermis layer.