The work herein reported is the University of Michigan's contribution to a larger scope dealing with the environmental impacts of outboard engine usage on small lake systems. This part of the total project is concerned with laboratory investigations. A wide variety of two-stroke engines were run under load conditions and the emissions, both condensable and noncondensables, analyzed. The influence of maintenance on emissions was also examined and found to have little effect. Crankcase drainage constituted only a small fraction of the total hydrocarbons emitted and was enriched in oil over the fuel. Exhaust products which one could reasonably expect to be condensable in a water-column constituted less than 10% of fuel fed in all cases and usually considerably less. The major portion of the water condensable aromatics evaporated fairly rapidly from the receiving water, but a portion was non-volatile. Analytical methods for field study were developed and the toxicity of both condensed exhaust and individual compounds in gasoline to goldfish were determined.