The interpretation of a reconnaissance gravity survey of north Queensland has shown that the area is composed of normal continental crust approximately 40 km thick, and is consistent with relief at the Moho of approximately 7 km. The parameters required for three-dimensional crustal gravity modelling, crustal thickness and density contrast across the Moho, were derived from available crustal seismic refraction experiments, together with analyses of correlations of crustal parameters on a worldwide basis. There are no large departures from isostatic equilibrium in the area. The southeastern part of the area is isostatically compensated and the crustal thickness reaches 43 km. The Mount Isa Block is not isostatically compensated and coincides with an area of thin (38 km) crust. This area is stable and, because of its size, is unlikely to achieve local isostatic equilibrium. The Cape York area has not reached isostatic equilibrium. The gravity anomaly pattern suggests that this area may have approached equilibrium progressively, with those parts of the area farthest from the centre of the Tasman Geosyncline having the smallest departure from isostatic equilibrium. This agrees with the history of development of the northern part of the Tasman Geosyncline, which youngs to the north and east. The Palmerville Fault is a major surface structure, but has no gravity effect originating at Moho depths, and hence may be only an upper crustal feature. The Coen Inlier also has little or no influence on the regional Bouguer anomalies, and is therefore probably a shallow crustal feature, of less significance than its surface outcrop suggests. The Cape York-Oriomo Ridge, however, has little surface expression, but is shown by the gravity data to be a major feature of the crust.