The use of liquids in animal nutrition is increasing, as it offers many advantages. Eurolysine proposes two kinds of liquid lysine, a low concentrated monohydrochloride ELL28 and a high concentrated lysine base LLB50. This presentation aims to set out our experience concerning the more concentrated product LLB50. Zootechnical trials on broilers and pigs have shown that equivalent performances are obtained with liquid lysine base and crystalline L-Lysine HCl. A description is given, including some characteristics of the product, the analytical method to determine the lysine content and its stability and compatibility with other liquid additives. The advantages of liquid lysine are developed, some of which are illustrated with data of our experiments. Key points for the success of liquid lysine utilization conclude the presentation.