Seven irradiation tests (with exposures of 0, 7.5, 15, 30, 60 and 90 krad) were conducted on 26 lots of grapefruit throughout the 1981–82 and early 1982–83 citrus seasons. Fruit treated with 60 and 90 krad showed rind breakdown and scald after storage for 28 days at optimum temperatures. Scald was the dominant injury in early-season fruit in tests conducted during Oct. and Dec. 1981 and Sept, and Oct. 1982. Rind breakdown, especially pitting, was the dominant injury in all other tests with midseason and late-season fruit. At the 7.5-, and 15-, and 30-krad exposures, injury was minimal, and fruit exposed to these dosages were acceptable. Although some 60- and 90-krad exposures resulted in excessive injury, 2 tests at 60 and 90 krad were acceptable with early fruit. In some instances, injured areas developed decay after storage and marketing conditions at 21°C.