Although serum amyloid A (SAA) was discovered almost 25 years ago, its biological role is still unknown. Similarly to C-reactive protein, SAA belongs to acute reaction proteins, synthesised in the liver after stimulation by proinflammatory cytokines like: TNFalpha, IL-1beta and IL-6. SAA level in acute inflammatory process of bacterial, mycotical, autoimmunological, oncological or extensive tissue damage is from 100 to 1000 mg/l. Additional SAA examination in patients with oncological disorders is accepted as a valuable survival index.