Two hundred and seventy xylan-grown colonies from caecal contents of 9 rabbits were examined microscopically after the Gram staining. Gram-negative irregular rods represented 40% of culturable xylanolytic isolates. Other isolates were Gram-negative cocci(16,5%), gram-positive rods (16%), gram-positive sporeforming rods (12,6%) and Gram-positive cocci (14,9%). Results of biochemical tests and fluorescence in situ hybridization allowed to identify 10 isolates. Another 7 isolates were identified using fluorescently labelled probes at the genus level. Xylanolytic enzymes were most active at pH 6.7-7.0.