Direct simulation Monte Carlo calculations are performed to study the heat transfer in laminar, rarefied flows past a circular cylinder. Results are obtained for flows with Knudsen numbers of 0.02 and 0.2; Mach numbers of 0.102 and 0.4, and also several cylinder temperatures are considered. Calculations show that these flows are attached except for the one with a Knudsen number of 0.02 and a Mach number of 0.4 in which separation occurs in the wake of the cylinder. Results are little affected by the changes in the outflow boundary conditions but show sensitivity to the domain size due to the subsonic nature of the flows. Mach number of 0.4 results show that when the cylinder temperature is higher than the free stream temperature by less than 10 degrees C, a net heat transfer occurs from the air stream into the cylinder which indicates that the classical convection heat transfer equation needs to be modified under rarefied conditions. The findings are in agreement with the limited data available in the literature.