The Phaeophycota is a group of marine benthic algae, commonly called as brown seaweeds. They derive their characteristic colour from large amounts of the carotenoid fucoxanthin in their chloroplasts.The amorphous component of their cell wall is made up of alginic acid and fucoidin, where as the mucilage and cuticle are composed primarily of alginic acid. They yield algin, which is used in the making og ice cream, dairy products, baking industry, rubber industry, paint industry and a wide variety of pharmaceutical products. They are also used a green manure for the soil and as food for animals and humans. The present knowledge about taxonomy of this significant group of organisms from the coast of Karachi is very fragmentary. Although there is a Luxuriant growth of brown seaweeds at the beaches of Karachi as well as in the nearby shelf area at the northern most part of undertaken to investigate in detail the species of brown algae occurring along the coast and inshore waters of Karachi for a better understanding of their taxonomy, growth and reproduction.