  Preliminary results on the flux of non strongly-interacting, fractionally
charged particles in primary cosmic rays at 400 Km above sea level are given.
Cosmic ray data collected by AMS-01 in June 1998 have been analysed on the
hypotheses of 2/3 charged leptons. The search is carried on by looking at the
energy deposition measurements by the time of flight system scintillator
counters. A preliminary flux limit is given.
