Thermal manikin experiments were carried out to investigate the effect of manikin surface temperature on the performance of a personal cooling system (PCS), more specifically, a liquid circulating garment (LCG). Three manikin temperatures were tested using a dry thermal manikin torso: 38, 34, and 30 degrees C. Mean environmental temperature during experiments was 23.5+/-1 degrees C. Results show that more heat was extracted from the thermal manikin by the PCS as the manikin surface temperature was increased. This is due to the larger difference in temperature between the manikin and the chilled fluid flowing in the PCS when the manikin temperature is high. Finally, it was demonstrated that if insulating garments that reduce heat losses to the environment were worn over the PCS, the PCS efficiency increased.