The brown seaweeds occupy a large area of Pakistan Coast and nearby continental shelf with a large EEZ of 200 sq km up to a depth of 110 m and show great variation in type and species. Most of the studies made in the past, were either on the taxonomy of brown seaweeds from the foregoing literature survey, it becomes apparent that most of the above mentioned studies were either on the taxonomy of brown seaweeds growing at the coast of Karachi or on ecological surveys about them, but such investigations lack information about their anatomy. There is a great lacuna of knowledge circumscribing infrastructural and pre-fertilization details of this important group of seaweeds, which is highly significant from the view-points of feed, fodder, fertilizer and industries of Pakistan. It is needed for understanding modern taxonomic and evolutionary position of the individual taxa. Therefore, it was imperative to conduct a thorough and detailed anatomical study of foliaceous and thalloid species of the phylum Phaeophycota growing at the coast of Karachi in order to understand their biodiversity. With this idea in mind the present study was undertaken.