A package based on a compression scheme for raw Illumina BeadArray data, designed to ease the burdens of sharing and storing such data. BeadDataPackR offers two key advantages over off-the-peg compression tools. First it uses knowledge of the data formats to achieve greater compression than other approaches, and second it does not need to be decompressed for analysis, but rather the values held within can be directly accessed. BeadDataPackR provides two functions. The function compressBeadData() takes the raw files and produces a .babfile from them, while the function decompress- BeadData() takes a .bab file and reconstructs the .txt and .locsfiles to the requested degree of precision. While the ability to reconstruct the original files is useful, given that many existing analysis scripts may expect the raw files, this step is not a necessity. Indeed, the structure of the file format means data can be extracted directly, allowing it to form the primary input to analysis tools.