Seeds of the field bean variety «Goiano Precoce» (Phaseolus vulgaris L.) were subjected to six gamma radiation dosages, comprising treatments from 0,0 to 6,4 krad. Effect on seed germination was studied by means of factorial experiments conducted under laboratory controlled conditions. The factors used were radiation dosages and nine increasing lenghts of time from date of seed irradiation. Seed vigor was determined by the rate of seedling emergence when planted in small field plots. A factorial design was used. The variables were the radiation dosages and six lenghts of time elapsed since date of seed irradiation. The following conclusions could be drawn from the results obtained: a) Seed germination was adversely affected by all radiation dosages in relation to the check treatment. This effect however decreased significantly with storing time. b) Seed vigor was higher for those treated with 0,4 krad, 0,8 krad and 1,6 krad when compared with those that were not irradiated. The 0,8 krad treatment was the most favorable.