Objective: Lower levels of long-chain omega-3 polyunsaturated fatty acids (n-3 LCPUFAs) and increased inflammation have been associated with both depressive disorder and myocardial infarction (MI). The present study investigated whether patients who develop depression post-MI, have higher arachidonic acid/eicosapentanoic acid (AA/EPA) ratios than non-depressed post-MI patients and whether depressed post-MI patients have signs of increased inflammation as measured by C-reactive protein (CRP). Method: Serum AA/EPA ratio and plasma CRP levels were quantified in 50 post-MI patients, of which 29 were depressed and 21 non-depressed. Results: Compared with the non-depressed group, depressed post-MI patients had significantly higher AA/EPA ratios. No significant difference was observed in CRP levels. Conclusion: Depressed post-MI patients had lower levels of n-3 LCPUFAs as measured by mean AA/EPA ratio and no signs of increased inflammation as determined by CRP levels.