Ulnar dimelia is a rare congenital disease with a characteristic range morphological of changes. These include duplication of the ulna, absence of the radius and polydactyly, although there is great variation of the changes seen in specific reports. Here I describe the main pathophysiological mechanisms, morphological variations as well as commonly used surgical strategies for this condition. For this purpose, I have screened the major databases to find the relevant literature and created a pooled analysis table for the morphological variations. The parameters used for the summarizing, include number of the upper limb fingers on the affected side, absence/presence of the thumb, type of the ulnar duplication, active and passive movement range, functional capability of the affected hand as well as the preceding events and the gender of the patient. For some of them I have discussed the surgical strategies and the long-term outcomes. All in all, this condition is characterized by a wide range of morphological variations. Further investigations should be performed to have a complete picture and strong classification algorithm for this extremely rare disease.