Electrical resistivity p of nickel-titanium alloys containing 0.0, 0.5, 0.8, 1.0 and 1.5 at. % Ti has been measured as a function of the absolute temperature T between 300 and 750°K. Each of the ρ vs. T curves exhibits a well-defined knee around the Curie temperature Tc. The concentration dependence of the Curie temperatures of these Ni-Ti alloys has been determined from our (dρ/dT) vs. T computer analyses.