‘Hyesun’, a new cultivar of leaf lettuce (Lactuca sativa L.) with sharply wrinkled oval and red leaf, produced by a cross between 'Nongjeockchima’ (red leaf color) and ‘Jeockchima’ (high yield) has late bolting and high yield in the field. The cross and selection for advanced lines had been done by the pedigree method from 2002 to 2008. The ‘Hyesun’ has gray seed color and medium elliptic leaves. The yield and adaptability of the advanced lines were evaluated at several locations of Korea (Gangwon-do, Gyeonggi-do, Chungcheongbuk-do, Jeollabuk-do, Gyeongnam-do, and Jeju-do) for 3 years (from 2009 to 2012). The type of maturity of ‘Hyesun’ is early-medium. The leaf hardness of ‘Hyesun’ is a 1,237kg/cm², which is not thicker than ‘Yeolpungeokchima’. The anthocyanin content of 'Hyesun' is a 88.32mg/100g, which is lower than that of ‘Yeolpungeockchima’. The BSL (Bitter Sesquiterpene Lactones, latucin + 8-deoxylactucin + lactucopicrin) content of ‘Hyesun’ is a 5.0ug/g of DW, which is lower than that of ‘Yeolpungeockchima’. Compared to ‘Yeolpungeockchima’, marketable yield of ‘Hyesun’ was higher by 7% (at 381g per plant) and the bolting time of ‘Hyesun’ was remarkably delayed under high temperature cultivation in the field. The shelf-life of ‘Hyesun’ was four weeks longer than ‘Yeolpungeockchima’ at 4°C. Furthermore, because ‘Hyesun’ is more crispy and sweeter than ‘Yeolpungeockchima’, ‘Hyesun’ has the better taste. So, we recommend that the new cultivar ‘Hyesun’ can be suitable for cultivation in both spring and fall season.