Evidence from studies involving zinc supplementation is equivocal. Carlson et al., (1999) stated that both early- and traditionally weaned pigs must be fed 3,000 ppm Zn for at least the first 2 weeks after weaning to enhance growth. Others have also demonstrated that weanling pigs exhibit increased growth performance when fed pharmacoloigcal concentrations of zinc (Zn) as zinc oxide (ZnO) (e.g. Hahn and Baker, 1993). However, the mode of action has not yet been fully elucidated. Specifically, there is no research available on the effects of pharmacological Zn concentrations on piglet gut morphology and gut microflora load. Accordingly a preliminary study was designed to examine the effects of dietary Zn and growth-promotant levels of avilamycin supplementation on gut morphological characteristic (villus height, width and crypt depth), together with gut microlflora characteristics, and digesta pH which is an independent factor influencing microflora colonisation.