Knee joint synovium was used for gene expression analysis of mouse collagen induced arthritis (CIA). Synovium was prepared at day 30 after initial sensitization from: healthy controls, CIA animals with no, with mild, with moderate, or with severe joint inflammation. Each sample group is represented by three replicates, each consisting of tissue collected from three to four animals. Experiment Overall Design: The data set consists of 15 samples: five groups with three replicates each. One sample group is from healthy controls, the other groups are from CIA animals with different degress of joint inflammation.