Atmospheric distribution of photochemical oxidants has been a subject of interest and concern not only because of their deleterious effects on human health and vegetation, but also because of their crucial role in determining the chemical composition of the atmosphere. The paper examines some issues related to the distribution and production of photochemical species and presents an analysis of results obtained from applications of a comprehensive three-dimensional regional scale photochemical model over the northeast United States. The Regional Oxidant Model (ROM) is used to simulate the response of various photochemical species to specific anthropogenic emissions strategies involving NOx and hydrocarbon reductions. Domain and temporal averages of predicted concentrations are examined for various species. Their relative influence on oxidant chemistry over the modeled domain is investigated. The relative benefits of reductions in NOx and hydrocarbon emissions on predicted ozone levels are also examined. Overall, model predictions show good qualitative agreement with expected trends.