Genome-wide location analysis of histone modifications and transcription factor binding relies on chromatin immunoprecipitation (ChIP) assays. These assays are, however, time-consuming and require large numbers of cells, hindering their application to the analysis of many interesting cell types. We report here a fast microChIP (μChIP) assay for 1,000 cells in combination with microarrays to produce genome-scale surveys of histone modifications. μChIP-chip reliably reproduces data obtained by large-scale assays: H3K9ac and H3K9m3 enrichment profiles are conserved and nucleosome-free regions are revealed.