Natural radionuclides such as 210 Po and 210 Pb were analyzed in soft part of cockle (Anadara granosa) obtained from Kuala Selangor in the west coast Peninsular of Malaysia. The activity levels of both nuclides fluctuated within the size of cockles from 41.3 ± 2.5 Bq/kg to 114 ± 7 Bq/kg and 12.9 ± 1.7 Bq/kg to 96.8 ± 5.3 Bq/kg in dry weight (dwt) for 210 Po and 210 Pb, respectively. The level activity in wet weight (wwt) also varied from 8.60 ± 0.52 Bq/kg to 25.70 ± 1.63 Bq/kg and 2.47 ± 0.40 Bq/kg to 19.27 ± 1.05 Bq/kg for 210 Po and 210 Pb, respectively, probably related to the different of metabolic rate and growth of cockles. Activity ratio of 210 Po/ 210 Pb in dry weight also fluctuated from 0.93 to 6.41 with not related to the decay of 210 Pb.