Membrane technologies were investigated with the aim to improve stability of C-Phycocyanin extracts resulting from ultrasonic breakage of Spirulina platensis. Five membranes, ranging from microfiltration to reverse osmosis, were utilized both for clarification and concentration steps. Nanofiltration with tubular organic membranes exhibited good performances: pigment recovery was 100%, mean permeation flux was 85 l h(-1) m(-2) for achieving a concentration factor of 7 with 30x10(5) Pa pressure and 1.5 m s(-1) tangential velocity (turbulent flow).