56 cases of proximal intraarticular tibia fractures over a 4-year period are reviewed. In every case the patients described a preceding valgus-compression trauma of their knee. Clinically we always found a hemarthrosis combined with a tenderness on pressure at the fractured condyle. Roentgenograms should be performed in 4 projections, eventually followed by conventional tomograms or computed tomography. Frequency of the several fracture types is demonstrated following the classification of the AO working group for osteosynthesis. The Eminentia intercondylaris was concerned in 13 cases as avulsion fracture of the anterior cruciate ligament (ACL) with a double peak distribution in the under 20-years- and over 40-years-age group. In the remaining cases we observed split- and/or compression fractures of the lateral tibial plateau of the 40 to 60 year old skier, in 20% communitive fractures. In 85% of the ACL-avulsion fractures we applied a cast brace as a conservative measure, whereas 75% of the tibia plateau fractures were treated operatively by mean of open reconstruction of the articular surface and internal fixation based on the AO-principles as well as bone graft buttressing in two third of the cases.