Determinants of infant pain responses are important when assessing the efficacy of analgesics. In a randomized controlled trial, 106 infants aged 2 to 6 months were positioned either supine (SUP) on the examination table or held (HLD) by a parent during routine immunization in a community pediatric office. There was no difference between the SUP and HLD infants in duration of crying, facial grimacing or visual analogue scale (VAS) pain scores. Similarly gender did not affect pain response. In contrast, 2-month-old infants displayed more pain during immunization than did 4 or 6-month-old infants.