Details are given of the culture apparatus and methods found successful for the laboratory culture of species of Ectocarpus. In attempts to obtain uni-algal cultures of this genus several common methods were tried but only one of them, a modification of the plating technique, proved successful. Methods of washing and dilution were unsuccessful in giving bacteria-free cultures, presumably due to bacteria closely adhering to the cell walls. Ultraviolet irradiation was also unsuccessful but treatment with penicillin gave bacteria-free cultures of E. confervoides and E. secundus (Giffordia secunda).