Bioaccumulation and elimination of tributyltin (TBT) and triphenyltin (TPhT) in different culture mediums (A, control; B, 0.40 µg- TBT/L; C, 0.40 µgTPhT/L; and D, 0.20 µg-TBT/L + 0.20 (gTPhT/L) for 15, 30, 45 and 60 days in oysters (Crassostrea gigas) and for 59, 73 and 92 days in rock shells (Thais clavigera) have been carried out at Tungkang Marine Laboratory. The test animals were collected from the northern (Shiangsan: 24û46’02” N, 120û54’05” E) and southern (Chiku: 23û03’ 45” N, 120û04’37” E) oyster mariculture areas on the west coast of Taiwan in August 2000. Results indicated that no hermaphroditic oyster was observed when cultured in different TBT and TPhT mediums for 60 days. For rock shells, after 92 days, only male (TBT, 2188 ± 21 ng/g) survived in medium B; while both females (TPhT, 2107 ± 30 ng/g) and males (TPhT, 2013 ± 17 ng/g) were found in medium C. No elimination of TBT and TPhT in imposex, female and male rock shells were observed while such elimination was found in both female and male oysters. High bioaccumulation rates of TBT in male (oyster, 10.7 ng/g/day; rock shells, 55.5 ng/g/day) and that of TPhT in female (oysters, 14.5 ng/g/day; rock shells, 27.1 ng/g/day) as well as high rates of TBT (20.0 ng/g/day) and TPhT (24.6 ng/g/day) in imposex rock shells were observed. Some experimental results on the effects of bioaccumulation and elimination of TBT and TPhT on sexual characteristics (male, female, imposex or hermaphroditic) of rock shells and oysters were discussed and evaluated.