One species of the red algae (Rhodophyceae) resulted from carrageenan is Eucgeuma cottonii. This algae is cultured intensively in Madura island espicially in district of Sumenep in village of Pekandangan - Buto. Production of E. cottonii in Sumenep - Madura rised over the last years but extraction of carrageenan has not been performed extensively. Unfortunately, it has been exported to abroad in dried from used as raw materials either food or non food industry. The objective of this research is to stydy the influence of extraction method of carrageenan on its quality. The best carrageenan quality was resulted by the modification of extraction metod by using cold alkali treatment so this method can be considered as alternative methods. The carrageenan quality that serulted from this methods is one the standard suggested by food and agriculture Organization,