Recent studies have shown that wild ruminants are sources of previously un-described microorganisms, knowledge of which can improve our understanding of the complex microbial interactions in the foregut. Here we investigated the microbial community of 7 wild-caught giraffes (Giraffa camelopardalis), 3 of which were fed natural browse and 4 were fed Boskos pellets, leafy alfalfa hay and cut savanna browse, by characterizing the 16S rRNA gene diversity using 454 FLX high throughput sequencing. The microbial community composition varied according to diet, but differed little between the ruminal fluid and solid fraction. The giraffe rumen contained large levels of the phyla of Firmicutes and Bacteroidetes independent of diet, while Prevotella, Succinclasticium and Methanobrevibacter accounted for the largest abundant taxonomic assigned genera. However, up to 21% of the generated sequences could not been assigned to any known bacterial phyla, and approximately 70% not to genus, revealing that the giraffe rumen hosts a variety of previously undescribed bacteria