Objective: To report clinical outcome after use of an interlocking nail (ILN) for stabilization of diaphyseal fractures in dogs and cats. Study design: Prospective study. Animals: Six client-owned dogs and cats. Methods: Interlocking nails (4 or 5mm diameter for 3 cats and 6 or 8 mm for 3 dogs) were used in femoral diaphyseal fractures treatments. Data about the patient (species, breed, weight, age), characteristics of the fracture, details of the surgery and perioperative complications were recorded. We evaluated functional outcome and fracture healing at 30 and 60 days after surgery. Results: Femoral fractures in 3 dogs and 3cats were repaired. Two of the fractures were comminuted. Clinical outcome was excellent in all cases. The six cases were x-ray evaluated at 60 days after surgery and healed without complication. Conclusion: The high success rate associated with a functional outcome suggests that ILN can be used to stabilize diaphyseal fractures in dogs and cats.