A new lettuce cultivar ‘Misun’ (Lactuca sativa L.) with wrinkled traverse narrow elliptic and deep red leaf, which has late bolting and high yield. It was developed from a cross between ‘Yeoreum Jeocgchima’ (deep red leaf color) and ‘Yeoreum dukseomjeokchukmyeon’ (high yield). The cross and selection for advanced lines had been done by the pedigree method from 2001 to 2008. The advanced lines were evaluated for yield and adaptability at several locations in Korea (Gangwon-do, Gyeonggi-do, Chungcheongbuk-do, Jeollabuk-do, Gyeongnam-do, and Jeju-do) from 2009 to 2011 year. The ‘Misun’ has gray seed color and traverse narrow elliptic leaves. The shelf-life of ‘Misun’ was four weeks longer than ‘Dukseomjeokchukmyeon’ at 4°C. The anthocyanin content of ‘Misun’ (88.32 mg/100 g) was higher than that of ‘Dukseomjeokchukmyeon’(74.78 mg/100g). The BSL (latucin+8-deoxylactucin+lactucopicrin) content of ‘Misun’ (5.0 ug/g, DW) is lower than that of ‘Dukseomjeokchukmyeon’ (12.0 ug/g, DW). Compared to ‘Dukseomjeokchukmyeon’, marketable yield of ‘Misun’(289 g per plant) was 11% higher than that of it, showed good yield in fall season cultivation and has particularly improved expression of red leaf color at high temperature cultivation in the field. Furthermore, its taste is better, more crispy, and sweeter than those of ‘Dukseomjeokchukmyeon’. Thus, this new cultivar ‘Misun’ can be suitable for cultivation in low temperature during spring and fall season season.