A novel three-dimensional fragment-based classification system based on computed tomography findings was established to characterize femoral intertrochanteric fractures. The intertrochanteric bone fragments were defined as follows : neck, posterior portion of the greater trochanter, anterior portion of the greater trochanter, lesser trochanter, and shaft. Each type of fracture was classified as 2-, 3-, 4-, or 5-fragment according to the number of floating bone fragments. Following the description of the fracture type, each floating bone fragment was appended, with the exception of a fragment involving the shaft. Ninety-five intertrochanteric fractures were classified by the same surgeon. The fractures occurred in 14 men and 81 women with a mean age of 84.7 years. The frequency of each type of fracture was investigated. Thirty-one fractures (32.6%) were 2-fragment and 64 (67.4%) were ≥ 3-fragment. A fragment of the anterior portion of the greater trochanter, which cannot be classified using conventional systems, was included in 29 cases (30.5%). A 5-fragment fracture was detected in two cases (2.1%). Using this fragment-based classification system, intertrochanteric fractures can be evaluated in more detail than is possible using conventional classification systems.