Leading charm production in reaction π − N → DX is discussed. Three experiments at Fermilab and CERN have measured a rather large enhancement in production rate of leading D −-mesons over nonleading D +. A good description of these results is obtained in Quark Gluon String Model (QGSM) if the idea of ‘intrinsic charm’ is involved. The weight of the cc¯ pairs in the quark sea of colliding hadrons is estimated from the experimental data. The comparison with other theoretical models is also carried out.