Seasonality in biomass, thallus length and size classes of three Sargassum species, namely, S. baccularia (Mertens) C. Agardh, S. binderi Sonder ex J. Agardh and S. siliquosum J. Agardh, was analysed based on destructive sampling using line-transect-quadrat method from October to December 2008. Results showed that S. baccularia was most abundant among the three species. The plant was frequently found in the length class of 0 - 4.9 cm (79.68 %), and this was followed by S. binderi in length class of 5.0 - 9.9 cm (44.12 %), and S. siliquosum in the length class of 0 - 4.9 cm (66.67 %). The Sargassum species were observed to increase gradually in their biomass and mean thallus length further away from shore. Within three months, S. baccularia experienced a growth in its biomass and mean thallus length, while both S. binderi and S. siliquosum experienced a decrease in terms of biomass but an increase in their mean thallus length. Data also showed a correlation with environmental parameters, such as pH, DO, salinity, nitrate, phosphate and ammonia.