Calprotectin also known as MRP8/14 or S100A8/A9 is a heterodimeric complex of two S100 calcium-binding proteins: myeloid-related protein 8 (MRP-8 or S100A8) and MRP-14 (or S100A9). At present, according to many authors, it is considered that calprotectin MRP8/14 is a potentially more sensitive biomarker of disease activity in rheumatoid disease than conventional inflammatory indices such as the erythrocyte sedimentation rate, C-reactive protein and others. A review of the literature on concentration of calprotectin in patients with some rheumatic diseases (rheumatoid arthritis, juvenile idiopathic arthritis, adult-onset Still’s disease, systemic vasculitis, polymyalgia rheumatica, ankylosis spondylitis, systemic lupus erythematosus, and primary Sjögren’s syndrome) is presented.