Ram horns are waste materials from the meat industry. The objective of this study was to investigate the effects of various concentrations of ram horn (RHH) hydrolysate as a supplement on xanthan production from a local isolate of Xanthomonas campestris EBK-4 in batch culture. Firstly, ram horn hydrolysate was reproduced. The production of xanthan was influenced by the RHH. RHH supplementation promoted X. campestris growth, accelerated substrate metabolism, and increased xanthan production. A concentration of 3% v/v RHH resulted in the highest xanthan concentration (25.6 g/L) in 48 h. This value was 49% higher than that of control medium (17.1 g/L) in the absence of RHH in 60 h. The pyruvate content increased with increasing RHH concentrations. The application of RHH resulted in enhancement of xanthan production. (C) 2007 Elsevier Ltd. All rights reserved.