We have studied the influence of a polysulfated glycosaminoglycan (Arteparon) in comparison with indomethacin and piroxicam on the synthesis of prostaglandin E2 in Chinese hamster ovary cell cultures (CHO). The two non-steroidal anti-inflammatory drugs (NSAD) were found to be strong inhibitors of prostaglandin E2 (PGE2) synthesis. The inhibition was found to be dose-dependent. Arteparon, an antidegenerative drug for the treatment of osteoarthritis, was also found to inhibit PGE2 synthesis in the CHO cell cultures. The inhibition was not as strong as that of the NSAD and no correlation between the concentration of Arteparon and the inhibition of PGE2 synthesis could be demonstrated.