An 18-yr-old female orangutan (Pongo pygmaeus pygmaeus) developed opisthotonus after sustaining conspecific bite wounds 3 wk earlier. The orangutan developed progressive tetraparesis and dysphagia, despite normal mentation, suggestive of tetanus. A tetanus vaccine had been administered at 2 yr of age, but none since. Brain magnetic resonance imaging, computed tomography, cerebral spinal fluid tap, and bloodwork were unremarkable. Viral, Baylisascaris, and tetanus toxin testing were negative. A femoral central venous catheter (CVC) was placed to provide medications, fluids, and parenteral nutrition. The orangutan received human tetanus immunoglobulin, tetanus toxoid, penicillin, methocarbamol, and analgesia. After 1 wk, the catheterized limb became edematous; a deep vein thrombosis (DVT) was diagnosed ultrasonographically. A cephalic CVC was placed, the limb casted, intravenous therapy reinitiated, and enoxaparin started. The orangutan became mobile days later, and progressively improved. Despite no compliance with enoxaparin, the DVT resolved without residual signs. This is the first reported case of presumptive tetanus and DVT in a great ape.