MR spectroscopy of pathologically proven 26 ovarian mucinous tumors (9 benign and 17 malignant) was retrospectively evaluated. N-acetyl mucinous compounds (NAMC) peak at 2 ppm was observed in all 26 lesions. Lipid peak was observed in 1 of 9 benign tumors (11%) and 12 of 17 malignant tumors (71%). The presence of lipid peak for the diagnosis of malignancy had a sensitivity of 71%, specificity of 89%, PPV of 92%, and NPV of 62%. We conclude that the bimodal peaks of NAMC and necrosis-associated lipid are suggestive of malignant mucinous tumors.