The aim was to test whether male mice injected with (239)Pu citrate transmit induced mutations that lead to specific causes of death, decrease longevity or both. Male CBA/Ca mice injected with (239)Pu citrate solutions at nominal activities of 6 and 60 Bq g(-1) were mated to females (same strain) 54-68 days later. Absorbed doses to the testes were estimated to be approximately 0.3 and 4.0 cGy. Control males were injected with carrier only. Longevity was evaluated. All 1807 progeny were given detailed necropsies. Haematological analysis was used in an attempt to identify leukaemia. Male progeny from both treated groups lived significantly longer than those from the control, and there was no difference in longevity between the two treatments. No evidence was found of the induction of leukaemia or of any of the numerous probable causes of death. Although numerous significant differences were found in the many comparisons made between the three groups, there was no clear indication that any harmful effects were associated with paternal preconceptional plutonium exposure. This was in spite of the initial body burden (higher dose) being approximately 2800 times the maximum body burden allowed for workers when this study was initiated.