A rapid, selective and highly sensitive flotation method is developed for separation and enrichment of ultra trace amounts of Ag+ ion from water samples. At pH 6.0 and using sodium dodecylsulfate as a foaming agent, Ag+ was separated with bis(2-mercaptoanil)acetylacetone (BMAA) added to 1000 mL of aqueous solution. The proposed procedure of pre-concentration is applied prior to the determination of silver ion using inductively coupled plasma-atomic emission spectrometry (ICP-AES). The influences of pH, concentration of BMAA, applicability of different surfactants and foreign ions on the separation efficiency were investigated. The pre-concentration factor of the method is 1000 and the detection limit is 0.045 mu g mL(-1).