Available technical articles published during 1974, 1975, and 1976 on effects of heavy metals and toxic cations upon estuarine and marine flora and fauna were reviewed. For all articles, research effort generated by toxicant, by response parameter, and by major indicator organism assemblage was tabulated for field investigations and for laboratory studies. Most of the effort during this period was restricted to 5 metals (Zn, Hg, Cu, Cd, Pb) and 4 indicator groups (molluscs, telecosts, crustacean, algae). Laboratory investigators devoted a major portion of their workload to uptake, retention, and translocation studies, followed by studies on survival, on growth and development, reproduction, food chain transfer, behavior, respiration, body fluid chemistry, histology, and others, in that sequence. Results of field studies were confined almost exclusively to acquisition of data on baseline elemental composition and accompanying biotic and abiotic modifiers. Apparent limitations and deficiencies of current projects on biological effects assessment of metals and toxic cations in marine environments were presented and discussed. Suggestions were offered on direction and emphasis of future research in this subject area.