BACKGROUND Cancer screening aims to detect cancer at an asymptomatic stage, although side effects from screening also occur. We investigated the prevalence, longitudinal development, and predictors of psychosocial consequences of false-positive breast cancer screening. METHODS Three hundred ninety-nine women with false-positive screening mammography responded to the Consequences of Screening-Breast Cancer (COS-BC) questionnaire immediately after a negative diagnosis (free from breast cancer) following recall examination(s) (baseline), and 6 and 12 months later. Age-matched controls (n = 499) with a negative mammogram responded to the COS-BC at the same occasions. Five COS-BC scales (Sense of dejection, Anxiety, Behavioral, Sleep, and Existential values) were used as outcome measures. RESULTS Women with false-positive mammography had consistently higher prevalence of all five consequences compared with controls (P < 0.001). The prevalences decreased between baseline and 6 months (P < 0.001) but were stable between 6 and 12 months (P ≥ 0.136). Early recall profoundly predicted long-term consequences for all five outcomes (OR, 3.05-10.31), along with dissatisfaction with information at recall (OR, 2.28-2.56), being foreign-born (OR, 2.35-3.71), and lack of social support (OR, 1.13-1.25). CONCLUSIONS This 1-year longitudinal study shows that women experience psychosocial consequences of false-positive screening mammography. Early recall should be performed cautiously, and provision of information as well as social support may reduce psychosocial consequences. CONCLUSIONS Although delivery of population-based screening reduces breast cancer mortality, it also raises the issue of its impact on the psychosocial well-being of healthy women. Our findings identify predictors that can be targeted in future efforts to reduce the side effects of mammographic screening.