AIM: To provide a regional grid of reflection seismic data over the Saint Clair Trough, and to mature several leads on the southern flank of the trough, including the Woakwine feature identified earlier. Most of the area to be covered by the 1990 survey has not previously had any seismic coverage. The data to be acquired is intended to be of sufficient resolution to interpret possible structural detail within the Lower Cretaceous Pretty Hill Formation. METHODS: Survey dates: 11/1 - 27/2/90. Energy source: Vibroseis. CDP coverage: 6 000%. Recording mode: 120 channel digital - GEOCOR IV recorder. VP interval: 20.0 metres; group interval: 20.0 metres. RESULTS: 23 lines totalling 338 line km were acquired by Crew 1847 of Halliburton Geophysical Services, and processed in Brisbane, Qld, by Digicon. The Saint Clair Survey results achieved higher resolution, continuity and density than had any previous surveys in the region, particularly with improved definition of faults. Four reflector events representing the boundaries of three different stratigraphic units within the Pretty Hill Formation were mapped, to show the varying structural styles and depositional environments of potential source-reservoir-seal sediment packages as developed across the Saint Clair Trough, and which can be seen to extend up onto the adjacent basement highs. The regional dip of all the horizons mapped shows a north-south trend, with east-west oriented faulting. The throw of this faulting varies from 10 msecs at top Pretty Hill level to 100 msecs or more at intra-Pretty Hill levels. The tilted fault blocks now seen on all the dip seismic lines have clearly set up a series of fault-controlled structural traps with varying areal closures at different depths. One prospect and seven strong leads are described, with recommendations for further seismic work to resolve their respective trap sizes and play integrity. Interim potential reserve calculations for these traps are appended to the survey interpretation report.