Objective To compare the long-term psychosocial consequences of mammography screening among women with breast cancer, normal results and false-positive results.

Design A matched cohort study with follow-up of 12–14 years.

Setting Denmark from 2004 to 2019.

Participants 1170 women who participated in the Danish mammography screening programme in 2004–2005.

Intervention Mammography screening for women aged 50–69 years.

Outcome measures We assessed the psychosocial consequences with the Consequences Of Screening–Breast Cancer, a condition-specific questionnaire that is psychometrically validated and encompasses 14 psychosocial dimensions.

Results Across all 14 psychosocial outcomes, women with false-positive results averagely reported higher psychosocial consequences compared with women with normal findings. Mean differences were statistically insignificant except for the existential values scale: 0.61 (95% CI (0.15 to 1.06), p=0.009). Additionally, women with false-positive results and women diagnosed with breast cancer were affected in a dose–response manner, where women diagnosed with breast cancer were more affected than women with false-positive results.

Conclusion Our study suggests that a false-positive mammogram is associated with increased psychosocial consequences 12–14 years after the screening. This study adds to the harms of mammography screening. The findings should be used to inform decision-making among the invited women and political and governmental decisions about mammography screening programmes.