A series of 12 trials involving 1,710 crossbred pigs was conducted at eight geographical locations in the United States to determine the effect of avilamycin on average daily gain (ADG), average daily feed (ADF) and feed-to-gain ratio (F/G) of growing-finishing swine. Eight of 12 trials evaluated avilamycin concentrations at 0, 5, 10, 20, 40 and 60 ppm, while an additional four trials evaluated avilamycin concentrations at 0, 10, 20 and 40 ppm in swine grower and finisher diets fed ad libitum. All trials were conducted using a randomized complete block design with data from the 12 trials pooled for statistical analysis. Pigs fed 5, 10, 20, 40 or 60 ppm avilamycin had increased (P less than .05) ADG over control pigs. No differences were detected for ADF between control and avilamycin-fed pigs. Pigs fed 10, 20, 40 or 60 ppm avilamycin had improved (P less than .05) F/G over control animals. Average daily gain, ADF and F/G for pigs fed 0, 5, 10, 20, 40 or 60 ppm avilamycin were: 749, 763, 767, 769, 771 and 771 g; 2.38, 2.40 2.39, 2.41, 2.38 and 2.38 kg; and 3.17, 3.15, 3.12, 3.13, 3.09 and 3.09, respectively. Linear plateau procedures showed that the effective dose range of avilamycin for the growing-finishing phase is 5 to 10 ppm for improving ADG and 10 to 60 ppm for improving F/G.