We briefly summarize well established and the latest experimental results concerning the doping dependence of the so-called pseudogap (T*) and emphasize that surface related techniques, like ARPES or tunneling, give somewhat higher value of T* as compared to the bulk techniques, like specific heat. In the underdoped regime most theoretical models differ in extrapolating the T*-line to zero doping. As underdoped cuprates are rather inhomogeneous and the disorder plays an important role, the complete microscopic theory will have to take into account all these subtle effects. (C) 2001 Elsevier Science B.V. All rights reserved.