In the present study, the effects of intermittent ozone (IO3) application combined with low dose fungicide and high-dose dissolved ozone in water on storage life and quality of orange cv. Washington Navel were investigated. Harvested orange fruit were subjected to four different treatments: immersion in ozonated (4 mg L-1) water (OW) and only distilled water (Control) for 10 min, treatment with fungicide solutions containing 500 mg L-1 (half dose) and 1000 mg L-1 (common dose) imazalil (IMZ) for 60 s, respectively. Ozone and 500 mg L-1 IMZ treated fruit were kept in cold room under IO3 gas exposure (2.14 mg m-3) for 30 min at one-week intervals during cold storage. Other two groups (Control and 1000 mg L-1 IMZ) were stored at the same conditions without ozone exposure. Treated fruit were stored at 5 degrees C for 150 d. As a result, while the OW + IO3 treatment was more effective in reducing microbial load, 500 mg L-1 IMZ + IO3 was the best treatment for inhibiting decay rate of orange fruit during cold storage. Although the 1000 mg L-1 IMZ treatment provided a significant reduction in the initial microbial load, it could not maintain its effectiveness at the end of cold storage when compared to OW + IO3 treatment. The fungicide residue in 500 mg L-1 IMZ + IO3 treated fruit was significantly lower than that of common dose (1000 mg L-1 IMZ), as expected. The combined use of low dose IMZ with IO3 gas exposure also gave positive or at least similar results for quality losses compared to common dose during storage. Ozone and fungicide treatments significantly decreased the weight loss and respiration rate, and maintained the visual quality of orange compared to control. Collectively, these results suggest that 500 mg L-1 IMZ + IO3 and OW + IO3 treatments are potential techniques for maintaining the fruit quality of Washington Navel oranges during long term cold storage.