Twenty new heat flow values have been obtained from a relatively narrow zone of the Queensland Trough in the western Coral Sea. The average heat flow in the trough (60 mW/m2) is close to the world average. The heat flow is relatively high (generally over 69 mW/m2) in areas of basement (pre-Jurassic) high and basin margins but low (less than 55 mW/m2) in basin centers, decreasing with increasing sediment thickness. Steady state geothermal models suggest that the systematic decrease in the observed heat flow toward the basin center can be explained by the presence of low-conductivity sediments thickening toward the basin center. This study demonstrates the importance of heat refraction along the basin margins which causes broad variation of heat flow in a relatively narrow area. Although future detailed studies based on transient state solutions are necessary, the results of this study can be used for improved interpretation of paleo-heat flow and geothermal analysis of sedimentary basins. ¿ American Geophysical Union 1990