We address a new class of Information hiding on lossless data compression. In our model, secret information is embedded into a compressed data (e.g. ZIP) in a way that the compressed data can still be decompressed by regular decompression process (e.g. UNZIP). The entity with secret key can extract the secret information from the compressed data. In this paper, we formally define the above model of information hiding on lossless data compression. Then, we focus on a particular compression method, namely LZSS, which is adopted in ZIP/LHA. We propose a new method, called IH-LZSS, that controls the trade-off between themaximum embeddable data size and compression rate. Some experimental results are also shown.