Technical Abstract: Lentil (Lens culinaris L.) germplasm with sufficient winter hardiness to survive most winters in cold northern areas is available; however, the use of that germplasm in breeding programs is hampered by variable winter conditions that make field evaluations needed for effective breeding and selection difficult. Our objectives in this study were to map the genes for winter hardiness, to gain additional information on genetics of winter hardiness in lentil and to identify markers for use in marker assisted selection. An F6 derived recombinant inbred line (RIL) population from the cross of WA8649090/Precoz was used. A total of 106 RILs was evaluated for winter survival in the field at Pullman, Washington, U.S.A, Haymana, Turkey, and Sivas, Turkey in a randomized complete block design with three replications for over three years. Winter survival was determined based on plant stand counts before and after winter. In addition, winter injury was monitored at Pullman during the 1998-99 winter season. Mean survival of the RILs was 49.7, 5.3 and 89.5% at Haymana in 1997-98, at Pullman in 1998-99 and at Haymana in 1999-00, respectively. For QTL analysis of winter survival, three QTLs were detected at Haymana in1997-98, one QTL was detected at Pullman in 1998-99, and three QTLs were identified at Haymana in 1999-00. Only one of the QTLs was common to all environments. For winter injury scores at Pullman in 1999, four QTLs were identified that influenced winter survival. Overall results indicated that winter hardiness is influenced by several genes and the cumulative effects of winter stress.