To evaluate and compare the levels of free fatty acids between senile cataract patients and normal controls. Fifty consecutive patients with newly diagnosed senile cataract and 50 age- and gender-matched controls were evaluated. Subjects/patients were randomized according to selection criteria. The levels of free fatty acids (FFAs) in serum were measured by gas chromatography-mass spectrometry (GC-MS). Sixteen fatty acids from 14:0 to 24:1 were identified. The values were compared between cataract and control groups by parametric independent sample test and Mann-Whitney U tests. A significant decrease was observed in arachidonic acid (C20:4n-6, ARA), cis-4,7,10,13,16,19-docosahexaenoic acid (C22:6n-3, DHA), tetracosanoic acid (C24: 0), cis-7,10,13,16,19-docosapentaenoic acid (C22:5n-6, DPA), total n-3 long-chain polyunsaturated fatty acids (LC-PUFAs), total n-6 LC-PUFAs, total fatty acids, unsaturated fatty acids (USFAs), polyunsaturated fatty acids (PUFAs), and nonessential fatty acid levels in patients with senile cataract in comparison with healthy persons (p < 0.05). The levels of FFA including DPA, tetracosanoic acid, ARA, and DHA were significantly lower in the senile cataract group compared to that in the normal controls. FFA may be helpful in preventing senile cataract.