The stability of deoxynivalenol and 3‐acetyl deoxynivalenol to irradiation by60Co‐gamma radiation under various conditions was investigated. Deoxynivalenol and 3‐acetyl deoxynivalenol were irradiated on maize, in aqueous solution and in the dry state. Breakdown of the toxins was monitored by high performance liquid chromatography. Both deoxynivalenol and 3‐acetyl deoxynivalenol were more sensitive to irradiation when irradiated in aqueous solution than when irradiated on maize. Breakdown of deoxynivalenol and 3‐acetyl deoxynivalenol in aqueous solution began at 1 kGy and 5 kGy respectively and both toxins were completely destroyed by 50 kGy. When irradiated on maize, breakdown of the toxins only began after irradiation to 20 kGy and 80 ‐ 90% of the toxins remained after irradiation to 50 kGy. Irradiation of the toxins did not cause the formation of new compounds of increased toxicity to baby hamster kidney cells. Both DON and 3‐A DON were stable to irradiation to 50 kGy when irradiated in the dry condition. The use of low dose gamma irradiation to destroy preformed toxins present on grain does not appear to be a suitable method for the detoxification of grain contaminated with deoxynivalenol and 3‐acetyl deoxynivalenol because of the high irradiation dose that would be required for their destruction (>50 kGy).