By the time a child in the UK reaches 13 months of age he or she should have received nine vaccinations. Therefore, it is important to look at interventions to decrease pain associated with receiving vaccines and to examine the evidence base for current clinical practice. This study (sample 72 babies randomly allocated to one or other treatment) was a small randomised, controlled trial to determine whether, when immunising babies aged two to six months, there is any difference in the perceived level of pain and distress experienced by babies when given two injections at the same time (simultaneous technique) as compared to giving them one injection after the other (sequential technique). Both practices are currently widespread. The study has shown that there is no difference in parents' perceptions of the distress experienced by babies receiving either simultaneous or sequential vaccinations. Preliminary findings of the observed measure of pain behaviour in babies report statistically significant differences in distress behaviours at four time points after vaccination between the sequential and simultaneous vaccinations, further research in a larger study is required to confirm these findings.