BACKGROUND: This study aimed to investigate differences in sucking behavior of infants bottle-fed with vented (so-called anticolic) teats (VTs) and nonvented teats (NVTs). METHODS: Trial design: Prospective, randomized clinical trial. Ninety-six term, healthy infants (aged 1–8 months) were assessed for eligibility. Seventy-three infants remained for intention-to-treat (ITT) and 65 infants (vented group: n = 31; nonvented group: n = 34) for the per-protocol (PP) analysis. During bottle-feeding, sucks/min, pauses/min, amount of formula intake (mL), feeding time (min), heart rate (bpm), respiratory rate (bpm), and oxygen saturation (%) were recorded. In addition, a parental survey was carried out to reveal possible symptoms of infantile colic. Sample-size calculation and confirmatory and exploratory analyses were performed using the Mann-Whitney U test and Fisher’s exact test. RESULTS: Except for the parameter sucking pauses per minute (NVTs > VTs, p = .03), no differences between groups were found with the ITT and PP analysis. After excluding infants with a disproportionately complementary diet (subgroup analysis, infants aged 1–6 months, n = 54) the primary outcome (sucks per minute) showed significant differences (NVTs > VTs, p = .01). The amount of formula intake, feeding time, and cardiorespiratory parameters were similar in both groups. The parental survey did not show any relation between types of feeding teats and possible symptoms of infantile colic. CONCLUSIONS: Compared with an NVT group, infants aged 1–6 months need fewer sucks and pauses when fed with VTs. In both groups, equal amounts of feeding medium and feeding time were observed. With NVT feeding, disruption occurs when the bottle vacuum is released by air from the oral cavity. Therefore, higher sucking frequency is needed to rebuild the oral vacuum for bottle milk flow, which implies higher risk of aerophagia. Overall, we suggest that the VTs provided a more coordinated drinking pattern than did the NVTs, which may have a positive effect on gastric distress.