In the paper some problems concerning of pyrogen testing were described. The risk of reactions after administration parenteral preparations contaminated pyrogenic substances give the cause for searching sensitive, repeated methods of their designation. The paper is review of the adaptation Limulus Amoebocyte Lysate (LAL) test for the estimation of endotoxin in biological preparations. The paper overview, chemical structure of endotoxin the characteristic of Limulus polyphemus, principle basis of the LAL test and general remarks of application. The LAL test according to the opinion of many authors is more sensitive in comparing with the pyrogen rabbit test.