The mono- and the digalactosyldiacylglycerol (MGDG and DGDG) galactolipids with a high content of polyunsaturated fatty acids, mainly omega-3, have been purified from the thermophilic blue-green alga ETS-05 that colonises the therapeutic thermal mud of Abano and Montegrotto, Italy. The therapeutic thermal mud is applied mostly to osteoarthritic cartilage patients. In the present study, a possible anti-inflammatory function of MGDG in cartilage has been studied in the avian articular cartilage model. We report that, in response to an inflammatory stimulus, adult avian articular cartilage cells express inflammation-related proteins, such as the lipocalin extracellular fatty acid binding protein, Avidin and Serum Amyloid A. The treatment of avian articular chondrocytes with the galactolipid MGDG suppressed the expression of the inflammation-induced proteins, suggesting a strong anti-inflammatory property of MGDG. MGDG has, in addition, a cell anti-proliferative activity, but it does not interfere with cell differentiation, suggesting a protective role for articular cartilage.