Pheromones released by male marine polychaetes Nereis succinea (Frey & Leuckart 1847) initiate egg release in mature females. Here we describe isolation and identification of components of the egg release pheromone bouquet from the coelomic fluid of sexually mature males. Inosine, L-glutamic acid and L-glutamine are identified to be components. Inosine, an egg release component, has a response threshold that is reduced eightfold by simultaneous presentation 1:1 with L-glutamic acid or L-glutamine. A fourth substance in the bouquet is tentatively identified as guanosine. The natural relative concentrations of all members of the pheromone bouquet and their mutual influence must still be explored.