An electrical imaging survey was conducted on the summit of Silbury Hill, Wiltshire, to investigate the area surrounding the recently collapsed remains of an antiquarian excavation shaft sunk by the Duke of Northumberland in 1776. It was hoped that the survey would reveal evidence for any near-surface archaeological remains threatened by the continued collapse of the shaft and identify unstable areas of ground where further subsidence might occur. Three trial profiles were also carried out on the flank of the hill. This work was intended to augment previous geophysical survey carried out at Silbury Hill by the Centre for Archaeology in February 2001. The survey detected a number of anomalies on the summit of the hill, two of which corresponded to features detected in trial trenches dug in April 2001. However, the interpretation of other anomalies is equivocal, and the suggestion of a further possible shaft is very tentative. One of the profiles on the flanks of the hill was impaired by wire mesh that had been inserted into the turf to protect it from erosion. However, the profile over the top of the Merewether tunnel did suggest a less homogenous structure to the chalk, possibly due to the tunnelling.