Objective A substantial dropout from the first dose of diphtheria-tetanus-pertussis (DTP1) to the 3rd dose of DTP (DTP3) immunization has been recorded in Pakistan. We conducted a randomized controlled trial to assess the effects of providing a substantially redesigned immunization card, centre-based education, or both interventions together on DTP3 completion at six rural expanded programme on immunization (EPI) centres in Pakistan. Methods Mother-child pairs were enrolled at DTP1 and randomized to four study groups: redesigned card, centre-based education, combined intervention and standard care. Each child was followed up for 90days to record the dates of DTP2 and DTP3 visits. The study outcome was DTP3 completion by the end of follow-up period in each study group. Results We enrolled 378 mother-child pairs in redesigned card group, 376 in centre-based education group, 374 in combined intervention group and 378 in standard care group. By the end of follow-up, 39% of children in standard care group completed DTP3. Compared to this, a significantly higher proportion of children completed DTP3 in redesigned card group (66%) (crude risk ratio [RR]=1.7; 95% CI=1.5, 2.0), centre-based education group (61%) (RR=1.5; 95% CI=1.3, 1.8) and combined intervention group (67%) (RR=1.7; 95% CI=1.4, 2.0). Conclusions Improved immunization card alone, education to mothers alone, or both together were all effective in increasing follow-up immunization visits. The study underscores the potential of study interventions' public health impact and necessitates their evaluation for complete EPI schedule at a large scale in the EPI system. © 2010 Blackwell Publishing Ltd.