BACKGROUND: The introduction of rotavirus vaccines in national immunization programs has decreased mortality and hospitalizations due to diarrhea. GSK\'s live-attenuated, human rotavirus vaccine (HRV) is a 2-dose vaccine for oral administration. Following the detection of porcine circovirus type 1 (PCV-1) in HRV, a PCV-free (no detection of PCV-1 and PCV-2 according to the detection limits of tests used) HRV was developed. The immunogenicity, reactogenicity and safety of a liquid (liq) PCV-free HRV were assessed in two prior studies. The present study aimed to generate additional reactogenicity and safety data. METHODS: This phase III, observer-blind, randomized, controlled multi-country study enrolled healthy 6-12-week-old infants. Infants were randomized to receive 2 doses of either the liq PCV-free HRV (N = 677) or the lyophilized (lyo) HRV (N = 674) 1-2 months apart. Solicited adverse events (AEs) were recorded for 8 days after each dose, unsolicited AEs for 31 days and serious AEs (SAEs) from dose 1 until the end of the 6-month safety follow-up. RESULTS: The occurrence of solicited general AEs was comparable between the liq PCV-free HRV and the lyo HRV groups, with irritability/fussiness being the most frequently reported (74.9% [95% confidence interval: 71.4-78.1] and 72.1% [68.6-75.5]). Unsolicited AEs were reported for 29.7% (26.3-33.3) and 30.6% (27.1-34.2) of infants in the liq PCV-free HRV and the lyo HRV group. A total of 39 and 38 infants reported at least one SAE, respectively. The most common SAEs were upper respiratory tract (0.7% and 0.9%) and urinary tract infections (0.9% and 0.6%). One SAE (constipation) in the liq PCV-free HRV group was considered as potentially causally related to vaccination by the investigator. No deaths were reported. CONCLUSIONS: The study showed that the reactogenicity and safety profiles of the liq PCV-free HRV and the lyo HRV are similar. CLINICALTRIALS: gov identifier: NCT0395474.