Eight trials were conducted during 2012–2014 to determine the response of non-2,4-D resistant soybean to 2,4-D tank contamination at 2.1–168 g a.e. ha-1. The predicted dose of 2,4-D to reduce yield 1%, 5%, 10%, 20% or 50% was 4.5, 22, 46, 97, and >168 g a.e. ha-1, respectively.