Statistical experimental designs were applied for the optimization of cell-bound phytase production by Pichia anomala in a cost-effective cane molasses medium. Using Plackett-Burman design, cane molasses, urea and inoculum density were identified as significant factors and these factors were subsequently optimized using a central composite design. The optimum variables that supported maximum enzyme titre were 8% cane molasses, 0.4% urea and 2% inoculum density. The validity of the optimized variables was verified in shake-flasks as well as in a laboratory fermenter. An overall 5- and 1.6-fold enhancement in phytase titres (324-1689 U/g DYB) and biomass production (6.4-10 g/l) were attained due to optimization, respectively. (c) 2005 Elsevier Ltd. All rights reserved.