The present study presents experimental results concerning the supercritical CO2 extraction of essential oil from Algerian rosemary leaves. The effects of key operating parameters such as pressure, temperature, particle size and CO2 mass flow rate on the extraction yield were investigated. The obtained yields were in the range of 0.95-3.52 g oil/g dry rosemary, and the best value was observed at a pressure of 22 MPa, a temperature of 40 degrees C, a flow rate of 7 g/min, and a particle size of 1 mm. The performance of the local rosemary used was assessed by comparison of the obtained yields with values reported in the literature for essential oils derived from different rosemary sources. The GC and the GC-MS analyses showed that the major compound detected in the essential oil was camphor, at 48.89 wt %.