OBJECTIVE: Loneliness has a deep impact on quality of life in older people. Findings on sex-specific differences on the experience of loneliness remain sparse. This study compared the intensity of and factors associated with loneliness between men and women. METHODS: Analyses are based on the 2008/2009 data of the KORA-Age Study, comprising 4127 participants in the age range of 64-94 years. An age-stratified random subsample of 1079 subjects participated in a face-to-face interview. Loneliness was measured by using a short German version of the UCLA-Loneliness-Scale (12 items, Likert scaled, ranging from 0 to 36 points). Multiple logistic regression analysis was conducted to analyze the associations of socio-demographic, physical, and psychological factors with loneliness. RESULTS: The mean level of loneliness did not significantly differ between men (17.0 ± 4.5) and women (17.5 ± 5.1). However, among the oldest old (≥85 years), loneliness was higher in women (p value = 0.047). Depression, low satisfaction with life, and low resilience were associated significantly with loneliness, which was more pronounced in men. Living alone was not associated with loneliness, whereas lower social network was associated with a three time higher risk for feeling lonely in both men and women. CONCLUSIONS: The extent of loneliness was equally distributed between men and women, although women were more disadvantaged regarding living arrangements as well as physical and mental health. However, loneliness was stronger associated with adverse mental health conditions in men. These findings should be considered when developing intervention strategies to reduce loneliness.