A four-year-old Saanen goat, weighing 52 kg, was referred to the Department of Obstetrics and Gynaecology clinic with black discoloration of the left mammary gland. The goat's general condition was not good upon initial examination. The goat was anorexic, lethargic, and febrile ( rectal temperature of 40 degrees C) with a palpably cold left mammary gland on which there was an accumulation of pus. Somatic cell count (SCC) was measured as 820,000/ml in the milk sample collected from the infected gland, and Staphylococcus aureus was isolated. Gangrenous mastitis was diagnosed on the left mammary gland of the goat based on the clinical findings. To treat the condition, a unilateral mastectomy was performed successfully. The goat was fully recovered a week after surgery. This case aimed to establish a surgical approach of unilateral mastectomy as a treatment option for goats with gangrenous mastitis while allowing the other mammary gland to continue lactation. Thus, it can be concluded that unilateral mastectomy is a viable alternative treatment of goats with gangrenous mastitis. (C) 2015 Faculty of Veterinary Medicine, Cairo University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license.