Assessing the ulnar trochlear notch (UTN) radiographic anatomy has been considered important, but difficult, in the diagnosis of elbow dysplasia. The purpose of this study was to evaluate UTN curvature of natural elbows in radiographs, using a methodology applied to disarticulated joints. The methodology was implemented and validated using dedicated software created by the authors. Mediolateral extended (MLE) and mediolateral flexed (MLF) elbow views were used from 20 joints from canine cadavers that were over 20 kg. After arranging the bones to avoid radiographic overlapping of the bones, an additional mediolateral radioulnar (MLRU) view was made. Curvature radius measurements from the central ridge of the UTN of each elbow were acquired in the MLRU view, using the software. The measurements were repeated in a second session, to determine repeatability. Then similar UTN measurements were taken from the MLE and MLF views, to determine reproducibility. Intraclass correlation coefficient (ICC) for repeatability and reproducibility of measurements were above 0.98 (95% confidence interval limits >0.75). The 95% limits of agreement (LA) for repeatability were 22.98 to 3.19 mm. The 95% LA for reproducibility between MLRU and MLE views were 24.32 to 3.75 mm. The 95% LA for reproducibility between MLRU and MLF views were 25.02 to 4.07 mm. The methodology and software are determined to be both precise and suitable to evaluate the UTN in MLE and MLF elbow views of large breed dogs, for anatomical and clinical purposes. In the future it would be useful to characterize normal and dysplasAbbreviations used: CI 5 confidence interval; ICC 5 intraclass correlation coefficient; LA 5 limits of agreement; MLE 5 mediolateral extended elbow view; MLF 5 mediolateral flexed elbow view; MLRU 5 additional mediolateral radioulnar view; MLRU 1 5 second session of measurements in the MLRU view; SD 5 standard deviation; SEM 5 standard error of the mean; UTN 5 ulnar trochlear notch; d 5 mean difference; f 0 5 first derivative of the polynomial fit to the points; q 5 Radii of curvature; r 2 5 correlation coefficient; s* 5 normalized natural coordinate; f 00 5 second derivative of the polynomial fit to the points.