Data are presented describing critical current densityJcas a function ofHa, applied magnetic field, for NbTi alloys containing between 22 and 38 at.% Nb. The effect onJc(Ha) of precipitation heat treatments between 275 and 565°C was studied in conjunction with cold area reductions up to 99.9%. The highest critical current densities,Jc(Ha), were in the range 1.0 to 3.6×105A/cm2at 3.0 T where most of the data were obtained. Critical temperature data are presented as a function of alloy composition and metallurgical preparation.