  We reconsider the problem of the origin of Low-Surface-Brightness (LSB)
galaxies within the standard Cold Dark Matter (CDM) cosmological model ($\Omega
=1, h=0.5$). Taking into account the effect of substructure on the collapse
times of low overdensity peaks, we show that the abundance of these peaks is
larger than previously expected because of the dragging caused by dynamical
friction induced by the presence of small-scale substructure. The number
density of these shallow, low-density peaks turns out to be in good agreement
with the observed overdensity of the blue LSB galaxies found during recent
surveys.
