Interests in the use of borate crystals in ultraviolet nonlinear optics have increased because all-solid-state UV lasers obtained with NLO crystals are in highly demand for scientific and industrial applications. Recently, new borate crystals, CsLiB 6 O 10 and Gd x Y 1-x Ca 4 O ( BO 3)3 have been developed by the present authors. CsLiB 6 O 10 is for fourth- and fifth-harmonic generations of Nd:YAG laser, Gd x Y 1-x Ca 4 O ( BO 3)3 for third-harmonic generation. This paper reviews the growth and nonlinear optical properties of these new borate crystals and the progress in UV light generation.