Preliminary experiments were carried out in the Joint European Torus (JET) using 120keV helium (He) neutral beam injection (NBI). Injected power levels up to 5MW with 3He and 7MW with 4He, lasting up to 3s were reached. The 3s helium NBI produced efficient ion heating and similar global and local energy confinements to those obtained with deuterium (D) NBI, in both limiter and X-point plasma geometries, in L-mode and H-mode plasma regimes. The elimination of beam-plasma and beam-beam fusion reactions by replacing D NBI with He NBI extended the range for measuring ion temperatures with the JET neutron profile monitor and neutron spectrometers.