2006 Annual Report 4d.Progress report. This report serves to document research conducted under a specific cooperative agreement between ARS and the University of Illinois. Additional details may be found under the parent project 3611-21000-018-00D, Soybean Genetic Resources Management and Utilization. 133 F6 lines from IA3023 x LG99-11620 (A3 population) and 149 F6 lines from U98-311442 x LG00-8299 (B3 population) were grown at two locations in Illinois to map yield genes. LG99-11620 is from the cross of LG86-7754 x LG88-3146. LG86-7754 is an F5 line from PI 407720 x PI 407710 and LG88-3146 is an F6 line from PI 427099 x PI 445830. LG00-8299 is an F6 line from PI 574477 x PI 561377. Both populations were evaluated in 2005 at two locations in Illinois for plant height, lodging, maturity and seed yield. In the A3 population 7 QTLs were detected for agronomic traits, including one QTL for yield in which the favorable allele, derived from the adapted parent, increased yield by 270 kg/ha. The B3 population showed transgressive segregation for yield with the top ten progeny lines exceeding the adapted parent by 536 - 670 kg/ha, with an LSD of 295 kg/ha. A total of eleven QTLs were detected in the B3 population for agronomic traits including yield. Two QTLs for yield, one on LG A1 and the other on LG G, were detected consistently over environments. The LOD ranged from 2.7 to 4.9 and the QTLs explained 9.2 to 18.0 % of the phenotypic variation. The QTL on A1 is located 2 cM from a previously reported yield QTL. The QTL on G is located at Satt610, a location where, to our knowledge, a yield QTL has not been previously reported. The exotic parent contributes the favorable allele, causing a yield boost of 268 kg/ha.