Cetrimide Broth Base is recommended for cultivation of Pseudomonas aeruginosa from water samples using membrane filter technique. The composition and performance criteria of this medium are as per the specifications laid down in ISO 8360-2:1988. This medium is the modification of the formula designed by King, Ward and Raney and is useful for the cultivation of P.aeruginosa. This medium is also selective as it contains cetrimide (Cetyl trimethyl ammonium bromide), which inhibits other bacteria except P.aeruginosa. ISO Committee recommends Cetrimide Broth Base for cultivation of P.aeruginosa using membrane filter technique.