The present study evaluated the effect of modified atmosphere packaging (MAP, 5% O-2/50% CO2/45% N-2; treatment M), the addition of oregano oil (0.1%, v/w; treatment AO) as a natural preservative, as well as their combination (treatment MO) on the quality and shelf life extension of fresh Mediterranean swordfish fillets during a refrigerated storage (4 degrees C) period of 18 d. Simultaneously, swordfish fillets were stored under aerobic conditions (control treatement A, 4 degrees C) and on ice (usual commercial method of preservation, treatment 1, 0 degrees C). Among the 5 treatments examined in the present study, the most effective one to inhibit the microbial and sensory spoilage proved to be the MO treatment, achieving a shelf life extension of 8 to 9 d. The dominant bacteria in the microflora of swordfish, irrespective of treatment, were the Pseudomonads and the H2S-producing bacteria, while bothe lactic acid bacteria (LAB) and the Enterobacteriaceae produced the lowest populations in swordfish samples kept on ice. Among the chemical indices examined, thiobarbituric acid (TBA) values showed no specific trend of lipid oxidation for swordfish, irrespective of treatment. Final trimethylamine nitrogen (TMA-N) and total volatile basic nitrogen (TVB-N) values for treatments, A, AO, M, and MO ranged between 1.33 and 14.29 mg N/100 g and 14.11 to 55.52 mg N/100g, respectively, whereas for I samples they remained almost unchanged during storage. Sensory analysis (tasted attribute) correlated well with microbiological analysis, indicating a shelf life of approximately 5 to 6 d for control 10 to 11 d for AO, 12d for 1, 13d for M, and 14d for MO samples.