It has been found that the non-live vaccine against Diphtheria, Tetanus, and Pertussis (DTP) in addition to its disease specific effects may have so called non-specific effects with the potential to affect resistance towards vaccine unrelated pathogens, resulting in excess mortality and morbidity(Aaby et al., 2014). These immunomodifying effects may affect development of atopic dermatitis through increased immunological sensitivity(Nilsson, Gruber, Granstrom, Bjorksten, & Kjellman, 1998). A recent study from Australia found that delayed vaccination with the first dose of Diphtheria, Tetanus, and acellular Pertussis(DTaP)-containing vaccine is associated with reduced eczema (aOR: 0.57; 95% CI: 0.34-0.97, P = 0.04) and reduced use of medication against atopic dermatitis (aOR: 0.45; 95% CI: 0.24-0.83, P = 0.01)(Kiraly et al., 2016). The present study aims to test the above finding and investigate the effect of timeliness of vaccination with DTaP-IPV-Hib (with or without PCV) on development of atopic dermatitis before 1 year of age among Danish children born between 1997 and 2012. From 1997 to 2012 children in Denmark were scheduled to receive the 1st, 2nd, and 3rd dose of DTaP-IPV-Hib at 3, 5, and 12 months respectively.