Search for massive rare particles with the MACRO detector at Gran Sasso

Searches for massive penetrating particles in the cosmic radiation have been performed with the MACRO detector. Scintillators, streamer tubes (instrumented with specialized electronics) and nuclear track detectors have been used to search for signatures coming from magnetic monopoles (MMs); the scintillator and the nuclear track subdetectors were also used for searches for other rare particles (nuclearites, charged Q-balls). Based on no observation of such signals, we establish stringent flux limits, for MMs as slow as a few 10(-5)c.