ABSTRACT Quality of stored almonds is compromised by insect infestations and microbial contamination. Nitric oxide (NO) is a potent fumigant for postharvest pest control on fresh and stored products. NO fumigation must be conducted under ultralow oxygen conditions, and it always produces nitrogen dioxide (NO 2 ), depending on the O 2 level in the fumigation chamber. NO and NO 2 have proven antimicrobial effects but have not been tested for efficacy against microbes in almonds. We evaluated, in this study, fumigation of unpasteurized almonds with NO 2 at different levels for inhibition of bacteria and fungi. Almonds were fumigated with 0.1, 0.3, or 1.0% NO under ambient O 2 to generate 0.1, 0.3, or 1.0% NO 2 conditions; the fumigation treatments lasted 1 or 3 days at 25°C. GreenLight rapid enumeration tests on diluted wash-off almond samples from NO 2 fumigation treatments showed either greatly reduced microbial loads or complete control of microorganisms, depending on NO 2 concentration and treatment duration. NO 2 fumigation was more effective against fungi than against bacteria. These results suggest that postharvest NO fumigation with proper levels of NO and NO 2 can be used for insect and microorganism control on stored almonds. HIGHLIGHTS NO 2 fumigation was effective in controlling both bacteria and fungi on almonds. Complete control of bacteria and fungi was achieved in 1-day fumigation with 1.0% NO 2 . Postharvest NO+NO 2 fumigation has potential to control insects and microorganisms on almonds.