The article ‘‘Influence of the Energy Relationships of Organic Compounds on Toxicity to the Cladoceran Daphnia magna and the Fish Pimephales promelas,’’ authored by Giulio P. Genoni, recently appeared in Vol. 36 of Ecotoxicology and Environmental Safety. This information was questioned by T. Wayne Schultz. In such cases we offer the authors an opportunity to present a rebuttal and then both views are published simultaneously. In these rare instances, it is the further policy of the editors of EES not to allow a continuing dialogue, and the matter ends with this presentation. What follows, then, is Dr. Schultz’s comments and the rebuttal by Dr. Genoni.