Pheromones have been described in decapods, but not in Panulirus argus. To determine these attractants on urine of females P. argus 100 females were sampled from fishing areas of Isla de la Juventud, Cuba. Urine was extracted from bladders and subjected to a procedure to extract proteins. The proteins were run in two electrophoresis of polyacrylamide gel. In the first three, noticeable bands were observed. The second electrophoresis corroborated that these bands are subunits of one protein. Sponges soaked with protein material were exposed to individuals, resulting in attractiveness for males. It suggests that these proteins act as sex pheromones

Key words: Spiny lobsters, electrophoresis, attraction, sex pheromones