Late-stage diagnosis of breast cancer is associated with poor survival. Identification of individuals at high risk of late-stage diagnosis could be an effective step to reduce breast cancer mortality. We examined the association of socio-demographic factors and health behavior with breast cancer stage in a population-based sample of 380 female breast cancer patients in Saarland, Germany. Overall, 182 women (47.9%) were diagnosed with late-stage (regional or distant) breast cancer. After control for potential confounding by multivariate logistic regression, an increased risk of late-stage diagnosis was observed for older age (OR = 1.8; 95% CI 1.0-3.2), foreign nationality (OR = 3.9; 95% CI 0.7-20.8), living in large households (OR = 1.7; 95% CI 1.0-2.9), non-participation in general health check-up (OR = 1.5; 95% CI 0.9-2.4) and low interest in health care (OR = 1.6; 95% CI 1.0-2.7). The proportion of late-stage cancer was clearly decreased when tumors were detected by screening (OR = 0.4; 95% CI 0.2-0.8). Certain socio-demographic factors and characteristics of health behavior seem to represent independent risk indicators of late-stage diagnosis.