We attempted to determine if the selected lateral prophylactic knee braces (ie, Anderson Knee Stabler-101W, Don Joy-PKG and McDavid Knee Guard) were effective at stabilizing the medial collateral ligament against valgus loading to the knee joint. We tested 23 volunteer subjects under each of three braced conditions, plus a nonbraced condition. Applying stress to the lower leg of the subjects, we measured and recorded the linear displacement of the tibia in abduction and/or adduction. We analyzed the data, using a repeated measures ANOVA. There were no differences between the bracing conditions. We concluded that the three knee braces were not effective at stabilizing the knee joint from a static valgus force.