This research aims to quantify the impact of reminder invitations on uptake and cancer detection in Ireland. Examination of BreastCheck's clinical database (2000-2010) to determine number of women screened following first invitation and after reminder; comparison by age group and screening phase with outcomes of recall rate, cancer detection and true positive rates. Of 819,182 first invitations sent 448,974 (54.8%) women attended. 245,157 (66.2%) women attended after reminder invitations, increasing uptake by 29.9% to 694,131 (84.7%) and cancers detected by 1,550 (35%). Women awaiting a reminder were less likely recalled for assessment 9,555 (3.9%) than respondents to first invitation 2,887 (4.04%) (p=0.004). Younger, mainly initial women were more likely recalled for assessment after first invitation. There was no difference between cohorts for cancer detection rate or true positive rate. Reminders increased uptake, supporting international evidence. For programme efficiency attendance at first invitation is optimal. For maximum programme effectiveness attendance must be encouraged with reminders.