Vertical and marginal fractures of the patella are uncommon injuries compared with other types of patellar fracture. It's possible that they are more common than supposed, but often remain undiagnosed as acute injuries. Vertical and marginal fractures often results in less acute disability than stellate or transverse fracture and the routine radiographs are often unhelpful. Failure to diagnose acute vertical and marginal fractures of the patella, especially when the fragments are displaced, may result in prolonged disability of the knee and possible development of degenarative changes in the patello-femoral joint later. Twelve patients of the vertical and the marginal patellar fractures treated at St. Mary's Hospital from Feb. 1982 to Dec. 1987 were analyzed in clinical and radiological aspect. The results obtained from this study were as followings. 1. Vertical and marginal fractures had 15.4% of injury rate in all patellar fractures. 2. The fracture and its displacement were always present on the tangential view of the patella. 3. The mechanism of the fracture was s direct blow to the patella in which the affected knee was flexed. 4. The location of the fracture line was related to the degree of the flexed knee at the time of fracture. 5. Large separated fragments of the patella should be accurately reduced with rigid fixation in the rationale of the intraarticular fracture.