Pseudomonas aeruginosa culture contg. inorg. salts and glycerol was used for synthesis of the biosurfactant. The sort was purified by 2-stage ultrafiltration at 20 degrees C (pore diams. 100 kDa and 3-50 kDa). The retentate from the 1(st) stage was dild. with MeOH or EtOH to destroy the micellar structures. The recovery of rhamnolipid was higher than 90%. The crit. micelle concn. of rhamnolipid was 40 mg/L, surface tension its aq. soln. was 28,6 mN/m.