摘要:Background: The objective of this study is to determine whether analyze of the infant’s pain associated with diphtheria-pertussis-tetanus (DPT) immunization is useful for vaccination in children. It is not known whether the immunization pain can be prevented with the adequate choice of DPT vaccines among several manufacturers in Japan. Further, it is not clear whether the difference of the reaction during vaccination between gender and age. Design: Three manufacturer’s Japanese DPT vaccines were used in this study. The parents assessed their infant’s pain on a modified visual analogue scale (MVAS), the start of the crying and total crying time during the immunization. Results: The A manufacturer’s DPT vaccine was significantly lower on the proportion of crying, the duration of crying and MVAS score than the other two manufacturer’s DPT vaccines. The proportion of crying, the duration of crying and MVAS score was lower in the boy than in the girl. On the other hand, it had not found the difference of their reactions with age. Conclusions: Our studies have found that the adequate choice of DPT vaccine decreased vaccination pain. The studies also indicate that some tendencies with vaccinations were shown in children. To consider these tendencies was useful in performing less painful vaccination.