Technical Abstract: Soybean Phomopsis seed decay (PSD) is the major cause of poor seed quality in the United States, especially in the mid-south region. The disease is primarily caused by Phomopsis longicolla along with other Phomopsis and Diaporthe spp. There are few management strategies for this disease, and these strategies have not completely protected soybean against PSD. Breeding for resistant varieties is an effective way and a long-term strategy to control PSD. To identify new sources of soybean lines resistant to PSD, 45 maturity group III soybean germplasm lines from 28 countries were field screened along with PSD resistant and susceptible checks in 2009 at Kibler, AR, Stoneville, MS and Portageville, MO. Planting dates for AR, MS, and MO were June 5, May 20, and May 21, respectively. The experimental design was a randomized complete block with four replications. Seeds were harvested from each plot when the plants were mature. Seeds from each plot were tested for percent of seed infected by Phomopsis spp, percent seed germination, and visual quality. Some genotypes were resistant and some were susceptible to PSD across locations. PI 398697, PI 398752, PI417361, and PI504481 were among the lines with the lowest percentage of seed infection at each location. Soybean lines with low infection incidence, good visual quality, and high germination rate at all locations will be tested for resistance in 2010 field trials.