ObjectiveTo carry out a systematic quality review and meta‐analysis of all randomised trials ofmammographic screening that included women aged under 50 years.Data sourcesReports ofrandomised trials of mammographic screening were identified via MEDLINE and checks of the bibliographies of retrieved articles and reviews.Data synthesisIdentified trial were as essed for: (i) method of randomisation; (ii) documented comparability of baseline data; (iii) standardised criteria for breast cancer death; (iv) blinded review of cause of death; (v) completeness of follow‐up; and (vi) use of an “intent ion‐totreat analysis”. Seven randomised trial including almo t 160000 women aged under 50 were studied. The combined estimate of relative risk was 0.95 (95% confidence interval, 0.77‐1.18), a stati tically non‐significant reduction of 5%. Adju tment for the cluster randomisation of two trials, and for degree of compliance, did not substantially change this result.ConclusionsThese analyses suggest little, if any, benefit for women under 50 years of age. The results are not explained by the quality of the trials or the radiology. We recommend that women in this age group intending to be screened should be fully informed of the ere ults.