The design and performance of miniature ac susceptometers are described that are small enough to fit inside clamp type pressure cells. The susceptometers are comprised of a primary and a balanced pair of secondaries with numbers of turns as high as 1000 to optimize the coupling to the sample and hence measurement sensitivity. Two methods of balancing the vacuum signal of the secondaries are presented, making susceptibility measurements even in clamp cells generating large stray signals possible. With the technique presented here a comprehensive series of measurements was carried out into the pressure induced magnetic quantum phase transition of MnSi. ©1997 American Institute of Physics.