Significant growth of the biodiesel industry has lead to an increased availability of its principal by-product crude glycerol. This study deals with the production of lactic acid, using biodiesel waste-derived crude glycerol as a sole carbon source and ammonium sulphate as the nitrogen source. It was observed that 15 g/L of semipurified glycerol, 2 g/L NH4SO4, 0.03 g/L FeSO4.7H(2)O, 0.04 g/L MgSO4.H2O, 0.3 g/L MnSO4.H2O and 1 g/L Sodium acetate were the optimum concentrations for the production of lactic acid. Similarly, an incubation period of 40 h, pH of 6.5 and a temperature of 37 degrees C were found to be optimum. The results suggested that crude glycerol and ammonium sulphate could serve as a good cheap alternative, for the existing resources.