  We find non-critical string backgrounds in five and eight dimensions,
holographically related to four-dimensional conformal field theories with N=0
and N=1 supersymmetries. In the five-dimensional case we find an AdS_5
background metric for a string model related to non-supersymmetric, conformal
QCD with large number of colors and flavors and discuss the conjectured
existence of a conformal window from the point of view of our solution. In the
eight-dimensional string theory, we build a family of solutions of the form
AdS_5 x \tilde{S}^3 with \tilde{S}^3 a squashed three-sphere. For a special
value of the ratio N_f/N_c, the background can be interpreted as the
supersymmetric near-horizon limit of a system of color and flavor branes on
R^{1,3} times a known four-dimensional generalization of the cigar. The N=1
dual theory with fundamental matter should have an IR fixed point only for a
fixed ratio N_f/N_c. General features of the string/gauge theory correspondence
for theories with fundamental flavors are also addressed.
