Zygomycosis is an opportunistic fungal infection mainly involving patients with diabetes mellitus, immunodeficiency, and malignancies. The majority of cases reported as a post-transplant complication has been following renal or liver transplantation. Among those complicating heart transplantation, rhino-sinusitis and orbital mucomycosis comprise a little portion. A 38-year old heart-transplanted diabetic man returned to the transplant follow-up Clinique, 20 days after his successful operation with unilateral periorbital swelling, nasal discharge, and multiple cranial nerve dysfunctions. Multidisciplinary investigation and consultations resulted in detection of mucormycosis in paranasal sinuses and the orbital space, as well as complicating thrombosis of cavernous sinus. Surgical ablation of infected parts, along with antifungal regimen and adjustment of immunosuppressive maintenance was taken. Extension of craniofacial involvement was ceased as a result and allograft function remained undisturbed. Early detection of opportunistic infections in transplanted patients plays a great role in preventing from dissemination. Fungal infections, including zygomycosis, should be thought in recipients especially those carrying risk factors such as diabetes or who present with local unusual manifestations. Sinonasal and orbital mucormycosis, if diagnosed on-time, can be managed well to reduce mortality. Although devastation of one side facial and ophthalmic structures was inevitable in this case, the overall outcome was acceptable.