Mechanical attributes and techniques of applying the type I biplanar (quadrilateral) configuration of external skeletal fixation are reported. The apparatus was used clinically on 9 dogs and 1 cat with long bone fractures. Bony union occurred in these animals, but was slightly delayed in one. Return to clinical function of the limb generally was good to excellent. The instances of delayed union and poor clinical results are discussed to emphasize the use of good techniques of application and case selection.