The metabolism of gibberelline (GAs) in intact plants of Raphanus sativus was investigated. With [(2)H]GA feeds, [(2)H]GA1 from [(2)H]GA4, and [(2)H]GA4 and [(2)H]GA20 from [(2)H]GA9 were metabolized. Since [(2)H]GA20 was not converted into [(2)H]GA1, endogenous GA1 may have been biosynthesized from GA9 via GA4 rather than from GA20. The radioactivity of [(3)H]GA9 and [(3)H]GA20 was much more strongly transported among the plant organs than that of [(3)H]GA1 and [(3)H]GA4.