We introduce in this paper the notions of noncommutative (shortly, NC) CW-complex, noncommutative Serre fibration and show that up to homo-topy, every NC CW-complex algebra morphism is some noncommutative Serre fibration. We then deduce a six-term exact sequence for the periodic cyclic homology and for K-theory of an arbitrary noncommutative Serre fi-bration, or of a morphism in the category of...