Chloroform, methanol, chloroform: methanol (2:1 v/v ), hexane and petroleum ether extracts of Hypnea mu sciformis from the coast of Kanyakumari were tested in vitro for their antibacterial activities against Escheric hia coli, Salmonella typhi, Pseudomonas aeruginosa, Staphyloc occus aureus and Proteus mirabilis with the disc di ffusion method. Chloroform: methanol was the best solution for extracting the effective antibacterial material s from the Hypnea musciformis used in this experimental and co mpared with standard drug, Tetracycline . In the present study show the importance of in producing new bioactivity compounds having antibacterial activity.