The pressure and temperature dependence of the cloud point transition of an aqueous solution of an elastin-like polypeptide (MGLDGSMG(VPGIG)(40)VPLE), prepared by bacterial expression of the corresponding artificial gene, was measured. A temperature-pressure diagram was constructed over a wide range of conditions. The (VPGIG)(40) solution exhibited a well-defined pressure-induced cloudpoint (P-c), as well as a temperature-induced transition (T-c). From near atmospheric pressure up to 100 MPa, T-c increased with increasing pressure, but decreased with further increases in pressure above 200 MPa. The maximum T-c was reached at 100-200 MPa. Between 10 and 25 degreesC, the P-c decreased with increasing temperature, and a broad maximum in P-c was observed in the range -10 to 0 degreesC. These results are compared with our previous results on synthetic thermoresponsive vinyl polymers.