Enzyme activities of synovial membrane, synovial fibroblast and synovial fluid samples from arthritis patients. To determine enzyme activity, the following chromogenic substrates were used: (a) β-D-N-acetyl-glucosaminidase, (b) β-D-N-acetyl-galactosaminidase and (c) β-D-glucuronidase. Optical densities were measured at 405 nm. Rheumatoid arthritis (RA) synovial fluid (SFl) showed significantly higher enzyme activities for all tested enzymes as compared with osteoarthritis (OA) SFl. Synovial membrane (SM) and synovial fibroblast (SF) homogenates were characterized by significantly higher enzyme activities as compared with SFl samples. SFs showed significantly higher β-D-N-acetyl-glucosaminidase and lower or approximately the same β-D-N-acetyl-galactosaminidase and β-D-glucuronidase enzyme activity as compared with SM samples. *P < 0.05; **P < 0.01; ***P < 0.001.