In this paper wer present some features of Q-balls and we discuss their interactions with matter, and their energy losses in the Earth, for a large range of velocities. These calculations are used to compute the fractional geometrical acceptance of the MACRO detector. Furthermore a systematic analysis of the energy losses of Q-balls in three types of detectors is investigated. More specifically we have computed the light yield in liquid scintillators, the ionization in streamer tubes and the Restricted Energy Loss in the CR39 nuclear track detectors.