  We present high-resolution rotation curves of a sample of 26 low surface
brightness galaxies. From these curves we derive mass distributions using a
variety of assumptions for the stellar mass-to-light ratio. We show that the
predictions of current Cold Dark Matter models for the density profiles of dark
matter halos are inconsistent with the observed curves. The latter indicate a
core-dominated structure, rather than the theoretically preferred cuspy
structure.

Astrophysics