Statistical experimental designs were applied for the optimization of medium constituents for citric acid production by Yarrowia lipolytica NCIM 3589 in solid state fermentation (SSF) using pineapple waste as the sole substrate. Using Plackett-Burman design, yeast extract, moisture content of the substrate, KH(2)PO(4) and Na(2)HPO(4) were identified as significant variables which highly influenced citric acid production and these variables were subsequently optimized using a central composite design (CCD). The optimum conditions were found to be yeast extract 0.34 (%w/w), moisture content of the substrate 70.71 (%), KH(2)PO(4) 0.64 (%w/w) and Na(2)HPO(4) 0.69 (%w/w). Citric acid production at these optimum conditions was 202.35 g/kg ds (g citric acid produced/kg of dried pineapple waste as substrate).