The heterotrophic growth of C. vulgaris using crude glycerol as the sole carbon source was studied in five 5L flasks. Air in each flask was provided at a rate of 300 L/hr and the contents were continuously stirred with a magnetic bar. Temperature, pH and initial inorganic nutrients (nitrogen, phosphorus, potassium and micronutrients) were kept the same in all flasks. The C/N ratio varied in each of the five flasks was set at 6, 13, 25.4, 61.5 and 118 respectively while the nitrogen initial concentration was equal to 45.4 mg/L in all flasks. The residual organic carbon was measured as a function of cultivation time. It was found that biomass growth rates as well the lipid and protein content were dependent on the C/N ratio. Lipid content was proportional to the C/N ratio while the protein content was inversely proportional to the C/N ratio. Carbon concentrations above 2500 mg/L inhibited the growth rate.