Strain 268506(T) was isolated from a root of Avicennia marina collected at mangrove forest in Wengchang, Hainan province, China. The 16S rRNA gene sequence of strain 268506(T) showed the highest similarity with Micromonospora equina Y22(T) (98.8 %) and Micromonospora olivasterospora DSM 43868(T) (98.7 %). In addition, gyrB gene phylogeny clearly showed strain 268506(T) should be assigned to the genus Micromonospora but different from any established Micromonospora species. The predominant menaquinones are MK-9(H8) and MK-9(H6). The major fatty acids are iso-C16:0, iso-C15:0 and anteiso-C17:0. The characteristic whole-cell sugars are xylose, mannose and arabinose. The cell wall contains meso-DAP and glycine. Phosphatidylinositol, diphosphatidylglycerol and phosphatidylethanolamine are the characteristic polar lipids. The DNA G+C content is 70.3 mol%. Some physiological and biochemical properties combined with low DNA-DNA relatedness indicated that the novel strain could be readily distinguished from the closest phylogenetic relatives. On the basis of these phenotypic and genotypic data, strain 268506(T) represents a novel species of the genus Micromonospora, for which the name Micromonospora avicenniae sp. nov. is proposed. The type strain is 268506(T) ( = CCTCC AA 2012010(T) = DSM 45758(T)).