Microgravity effect on C. elegans gene expression was analysed by whole genome microarray. The worms were cultivated under microgravity for 8 days in the Japanese Module of the International Space Station. The samples of this study were divided three experimental groups: 1. microgravity for 8 days 2. artificial 1G control for 8 days on orbit 3. ground 1G control for 8 days This study was repeated with three biological and two technical replicates.