This study examined the historical changes of and dietitians’ needs for the Life Cycle-based Dietary Guidelines for Koreans. Content analysis of relevant documents, a survey of 307 dietitians, and in-depth interviews with eight dietitians were conducted. The dietary guidelines published between 2003 and 2004 included one set of common guidelines and several sets of dietary action guides corresponding to six target groups: pregnant and lactating women, infants and toddlers, children, adolescents, adults, and the elderly. The guidelines were revised between 2008 and 2011 and consisted of six sets of guidelines for the target groups without common guidelines. The dietitians considered five or six as appropriate numbers of guidelines for each group. Needs for separate guidelines for women of child-bearing age and male workers were reported. The dietitians preferred one set of common guidelines with specific action guides for each target group and wanted easier and more specific messages to be included in the new guidelines. It is suggested that the Life Cycle-based Dietary Guidelines for Koreans should be revised to reflect such dietitians’ needs.