Introduction: Lunate fracture is a rare injury. Most reports are associated with other wrist injuries such as perilunate dislocation and distal radius fracture. Isolated lunate fracture has been reported even more rarely. The choice of treatment and outcomes are consequently undetermined. Case Presentation: In this case report we will describe a lunate avulsion fracture as an isolated injury after a fall from nine meters treated operatively by excision of the comminuted avulsed fragment. After 33 months of follow-up radiographs showed no sign of degenerative joint disorder on simple X-ray, but slight Volar Intercalated Segment Instability (VISI) by a capitolunate angle of 26 degrees was noted. Clinically, the patient was pain free near full wrist and forearm range of motion and could perform his previous vocational and recreational tasks without any limitations. Conclusions: Despite apparently good short and mid-term clinical outcome, slight volar intercalated segment instability after 33 months of follow-up revealed that lunotriquetral ligament function was probably lost, which led to static instability. This ligament injury may be missed primarily. Excision of the avulsed osteochondral fragment should be the last option of treatment and most attempts should be tried to fix and/or restore the normal anatomy of ligamentous structure.