Seasonal variations in feeding physiology and scope for growth of green mussels Perna viridis (Bivalvia: Mytilidae) were investigated in Ma Wan, an estuarine mariculture site located in the southern waters of Hong Kong. Total particulate matter, particulate organic matter, particulate inorganic matter and organic fraction of seston (f), and food availability were monitored monthly from January to December 1998. Feeding rates, including clearance rate, filtration, ingestion and absorption, and absorption efficiency were higher in summer and autumn and lower in winter. Pseudofaeces were produced but the preferential selection of organic materials by P. viridis was not concluded. Scope for growth in  July and October were higher than in February. Activities of digestive enzymes including amylase and cellulase in the digestive diverticula and crystalline style were high in May and July and lower in February and October and correlated with f. Faster growth rates obtained for P. viridis in Hong Kong's summer are considered a result of enhanced feeding and absorption at high temperatures and f values.