Accumulation, distribution and depuration of inorganic mercury in the gills, viscera, mantle and adductor muscle + foot of green musselPerna viridis were investigated. Mussels were exposed to 37–5 and 75 µg 1−1 mercury as HgCl2 in a static system for 4 days. The rate of accumulation was found to be the maximum in gills followed by viscera, mantle and muscle + foot. Exposed mussels were then transferred to clean seawater in a flow-through system and maintained for 25 days to study the depuration and biological halflives (TB/2) of mercury in the different body parts. After 25 days, mercury loss from the external tissues like gills and mantle was faster than from the internal tissues like viscera and muscle. Gills and mantle showed comparatively shorter TB/2 than the viscera and muscle + foot.