A gravity survey was carried out at Iron Knob, during the period 28th July, to 14th August, in accordance with the recommendations and decisions made after the completion of the geomagnetic survey over the same area (vide progress report No. 3). A worden Gravitymeter was used for the gravity measurements. The levels at observation stations were determined by Dumpy Level Survey and Theodolite Stadia survey, the latter being used only over Lines 5100s, 4300s, B and C, where topography is irregular. Field work necessary for levelling and assistance in gravitymeter observations was provided by Messrs. H. Ridge and R. Mattner with one assistant. The excellent co-operation and adherance to programme requirements on the part of these officers and members of the Geological Staff contributed much towards the rate of progress and the planning of the programme. The principal features of the survey results were discussed, at the conclusion of field work, with Professor Rudd and members of the Geological staff. Similar discussions were held with Mr Hockey, in Melbourne, on 26th August. The purpose of this report and accompanying plans is to provide a detailed presentation of the survey results together with an outline of interpretation possibilities.