BreastCheck, the National Breast Screening Programme in the Republic of Ireland, invites women aged between 50 and 64 years biennially. A pilot intervention trial of invitation for screening of women not attending the previous appointment [previous nonattender (PNA)] was carried out that aimed at maximizing the efficiency of resources in terms of radiographer workload and scheduled appointment slots. The trial was conducted during screening round 5 at two of the regional units. The intervention arm implemented an alternative process for inviting PNA women, in which they were sent a letter inviting them to phone their screening unit to make an appointment at a convenient date/time. The control arm continued usual practice – that is, all PNA women were sent a single invitation letter with a scheduled appointment slot at a predetermined date/time. In the intervention arm, fewer PNAs took up their appointments (15.5%) compared with the control arm (18.3%; P<0.001). Uptake among PNAs fell in both arms between screening rounds 4 and 5 (intervention arm: 22.0% OSR 4, 15.5% OSR 5; control arm: 21.4% OSR 4, 18.3% OSR 5). There was a significant increase in mobile unit screening days saved because of the intervention and a significant improvement in the percentage of women reinvited for screening within 27 months in the intervention arm (85.5%). PNA recall and cancer detection rates were significantly higher compared with the general screened population. This trial showed an improvement in the efficiency of resource use. However, there was a higher cancer detection rate in PNA women. This trial provides important evidence for invitation policy for screening.