Dissolved amino acids and sugars produced by Chlamydomonas reinhardtii Dangeard and Euglena gracilis Klebs were assayed using a combination of radiochromatography and membrane separated spinner flasks. Both species produced similar complements of sugars. The sugars produced In the algae included galactose, glucose, maltose and xylose. The amino acid complements produced Were different for each species. C. reinhardtii excreted aspartate, leucine, methionine, phenlyalanine, tyrosine and Valine. E. gracilis excreted alanine, glutamate, proline and serine. Separation of cells from growth media via membrane filtration produced an overestimate of net amount of dissolved carbon compounds excreted by the cells. However, the radiochromatographic spectra for both filtrates and cell-free compartments of the diffusion flask experiments were identical. It is hypothesized that the process of filtration max enhance leakage of labeled cellular pools rather than cellular disruption in the species investigated.