Background: The allergen skin prick test is the most representative diagnostic test for atopy, but its use has been limited because of the belief that skin reactivity decreases with aging. Objective: To investigate skin reactivity and influencing factors in the elderly population. Methods: This cross-sectional analysis included 854 subjects (aged <65 years) who participated in the Korean Longitudinal Study on Health and Aging cohort (September 2005 to August 2006) and underwent allergen skin prick tests. Skin prick tests were performed with 1 mg/mL of histamine and a panel of 12 aeroallergens that are common in Korea. The wheal diameters were measured and compared to identify the factors associated with skin reactivity. Results: Older age and female sex were associated with reduced histamine skin reactivity in elderly subjects. This age-related decrease was apparent only among women, the reasons for which were not identified. In contrast to histamine, wheal response size induced by 2 major allergens, Dermatophagoides pteronyssinus and Dermatophagoides farinae, did not show sex differences and did not decrease with age among the subjects showing allergen-induced wheal size greater than 0 mm. Conclusions: This analysis demonstrates that age and sex can independently influence histamine skin reactivity among the elderly population. The allergen-induced wheal sizes did not decrease with age. The discrepancy between histamine and allergen skin reactivity may warrant further evaluation to redefine the cutoff value for the determination of a positive skin test result in elderly subjects.