Two groups of patients were studied, both in accordance with ACR criteria. First group (41 cases) suffering R.A. Second group (36 cases) suffering O.A. In both pathologies MMPs, ICAM and VCAM from synovial fluid and plasma were studied. Measurements were made with ELISA-sandwich in a Metrolab spectrophotometer at 410 nm for MMPs, and 491 nm for ICAM and VCAM. As control, samples of patients with noninflammatory muscle skeletal disorders or traumatic arthritis and healthy witness were used. Synovial concentration of MMPs in R.A. was 1402 +/- 76 ng/ml, a higher significant value (p < 0.0001) compared with osteoarthritis: 353 +/- 23 ng/ml. In the witness plasma, MMPs were not detected. Plasmatic and synovial levels of the adhesion molecules present different values in both pathologies and between them. Synovial ICAM level in R.A. (280 +/- 9.8 ng/ml) is significantly higher than in O.A. (163 +/- 10 ng/ml) (p < 0.001), but lower than the plasmatic ones (370 +/- 35 ng/ml) (p < 0.001). All these values are significantly higher than the normal plasma (121 +/- 6.5 ng/ml) (p < 0.01, p < 0.005, and p < 0.0001, respectively) VCAM increase regarding basal values (140 +/- 5.6 ng/ml) (p < 0.001) and in a similar proportion for both pathologies (R.A.: 186 +/- 9.3 ng/ml and O.A.: 207 +/- 14.3 ng/ml). Their plasmatic levels were higher (270 +/- 45 and 320 +/- 38 ng/ml) (p < 0.001) but without significative difference between them. There is correlation among MMPs, ICAM and VCAM variations. The variability can be explained by concomitance several evolutive steps. Each pathology shows a different grade of cellularity, inverted predominance in the relation TIMPs/ collagenase and different generator mechanisms of MMPs. Our findings reinforce the importance as diagnostic guide of adhesion molecules dosage, and possible therapeutic use of MMPs inhibitors and ICAM or VCAM antagonists en R.A. and related pathologies.