The molecular isolation of NPC1 and NPC2, the genes defective in patients with Niemann-Pick disease type C (NP-C), has heralded in an exponential increase in our understanding of this syndrome and thus of human intracellular sterol transport. Despite this, neither the mechanisms of action nor the substrates for these putative transporters have been defined. In this overview, we describe our perspectives on the current awareness of the genetic determination and cellular biology of this syndrome, with emphasis on the underlying events that lead to neurodegeneration and the manner in which they might eventually be treated.