A possible design for a more compact gas turbine engine uses contra-rotating high pressure (HP) and intermediate pressure (IP) turbine discs. Cooling air for the IP turbine stages is taken from the compressor and transferred to the turbine stage via holes in the drive shaft. The aim of this work was to investigate the discharge coecient characteristics of the holes in this rotating shaft, and, in particular, to ascertain whether the sense of rotation of the shaft with respect to the discs aected these signiยฎcantly. This paper reports mostly on experimental measurements of the discharge coecients. Some CFD modelling of this ยฏow was carried out and this has helped to explain the experimental work. The experimental results show the eects on the discharge coecient of rotational speed, ยฏow rate, and co-and contra-rotations of the shaft relative to the discs. The measured values of the discharge coecient are compared with established experimental data for non-rotating holes in the presence of a cross-ยฏow. For stationary shaft and discs, co-rotation of the shaft and discs and dierential rotation with the disc speed less than the shaft (in the same rotational direction), the discharge coecients are in reasonable agreement with these data. For dierential rotation (including contra-rotation) with the disc speed greater than the shaft, there is a signiยฎcant decrease in discharge coecient.