The study used skeletal parts archived at the Regional Forensic Center in Memphis, TN. The ribs of 43 blunt-force-trauma cases were analyzed, which involved 492 ribs and 733 individual fractures. "Incomplete fracture" was defined as any partial fracture, despite fracture location and morphology. Longitudinal cracks that followed the bone grain and unassociated with more complex fractures were unclassified and regarded as possible processing artifacts. "Buckle fracture" was defined as a fracture in which the bone failed at the point of compressive stress prior to failure at the point of tensile stress. The occurrence of incomplete (n=195) and buckle fractures (n=63) was calculated for the entire sample. The sample was then divided into subsets for additional comparison by age, sex, and race. The Wilcoxon rank-sum test was used to compare the subsets. Incomplete fractures, which were previously believed to be common in children but rare in adults, were found among individuals who ranged in age from 21 to 76 years. Buckle fractures, which had been previously undefined in bone-trauma literature, were repeatedly observed in the sample without significant difference in frequency among the subsets. The observation of both incomplete and buckle fractures reinforces the need to study bone biomechanics at the gross level. 3 tables, 4 figures, and 35 references