SUMMARYCultures ofChlorella vulgariswere grown aulo‐trophically under fluorescent light and heterotrophically on glucose and inorganic salts. Hydrocarbons were extracted and analyzed by gas‐liquid chromatography, molecular sieve separations, and silicic acid‐AgNO3chromatography.Chlorella vulgarisgrown under both culture conditions contained a series of saturated n‐paraffins ranging from 17 to 36 carbon atoms in length. This is in contrast to reports in the early literature which indicated that the hydrocarbon fraction of algae was composed of only 1 or 2 specific hydrocarbons. Only under heterotrophic conditions, however, didC. vulgarisproduce 1‐penta‐cosene and 1‐heptacosene as the primary components of the hydrocarbon mixture. OtherChlorellaspecies were examined, but onlyC. vulgarisproduced significant quantities of th