An original pragmatic approach is presented for priority setting among existing chemicals, as a result of a study requested by the European Community Commission. On the basis of a set of physicochemical, toxicological, and ecotoxicological properties considered as fundamental for a first evaluation of the substance, the proposed system develops a score for each property in both the presence and absence of the datum. The properties in this first set are considered additive. Other information on the substance (quantity on the market, plurality of possible exposures, bioconcentration, environmental diffusion, persistence and size of risk population) is included in a second set of multiplier parameters. Through this simple and self-improving system it is possible to work out, using different final formulas, different lists for different needs. Using 30 well-known substances as examples with which to check the system, it is possible to see how these substances distribute themselves as to priority for environmental or for direct personal exposure.