Dielectric and piezoelectric properties of K(Ta0.51Nb0.49)O3 [KTN] single crystals along [100], [001] and [011] pseudo-cubic crystallographic orientations are reported and discussed. Temperature dependencies of dielectric permittivity in tetragonal phase of monodomain and polydomain crystals of these orientations are compared. Strong dielectric anisotropy is found in the tetragonal phase, with ε[100] / ε[001] ratio equal 16 at 300 K. Room temperature piezoelectric coefficients for the monodomain state of KTN are reported.