Three hundred clams were placed in sediment in a continuous flow seawater tank between March and June. The tank was dosed with 14C labeled benzo(a)pyrene in no. 2 fuel oil daily. Animals were removed weekly and assayed for accumulation of the radioactive material. On the sixth, thirty-third and sixty-first day of exposure animals were removed from the dosing tank, placed in sand substrate with flowing seawater for depuration and again monitored weekly for remaining radioactivity. It was found that above a large variability and fluctuation there was a gradual trend toward increased accumulation over a 90 day period. Depuration is moderately rapid and resembles a first order decay curve. Biological half-life ranged between 5.5 and 9 days. The depuration rate appeared to be somewhat slower upon prolonged accumulation. This is compared to PNA depuration rates from field animals.