The aim of the study was to evaluate whether mass-mailing of a 12-month wall calendar which focused on child and infant safety and first aid treatment had any educational effect on lay people. The calendar included algorithms for removal of a foreign body from the airways and infant and child CPR. The knowledge and skills in these procedures were tested in two groups using a previously validated check-list before and after the introduction of the calendar. One group received the calendar by mass mailing, free-of-charge. Six months after calendar distribution the mean result for 52 persons tested was 18% correct, not different from the 19% correct for 65 persons tested before calendar distribution. The other group received the calendar as part of an internal company campaign focusing on infant and child safety with a possibility for borrowing a baby manikin, but with no instruction involved. In this group the mean result improved significantly from 27% precalendar (n = 57) to 47% (n = 125) (P < 0.001) 1 week after calendar distribution with a significant reduction to 38% (n = 52) (P = 0.004) 6 months later, still significantly better than precalendar (P = 0.004). Test persons younger than 50 years old scored better than those older than 50 years (39 vs. 22%, P < 0.001), and the test persons scored better if they had been tested previously (44 vs. 35%, P = 0.04) or had practised with a baby manikin (45 vs. 35%, P = 0.02). Whether the test persons had children 0-8 years old or not, did not affect the results. In conclusion the calendar had no educational effect when distributed by mail, but a safety campaign which included distribution of the calendar and a possibility to borrow a manikin had a positive influence on the first aid skills and knowledge of lay people. Mass mailing of CPR or other first aid material free-of-charge does not seem to further the goal of increasing the rate and proficiency of bystander interventions to save lives.