The combination of two regimes of enhanced performance, the H mode and the pellet-enhanced- performance (PEP) mode, has been achieved in JET. The strong enhancement of the central plasma parameters, obtained with pellet injection and subsequent auxiliary heating, are found to persist well into the H mode phase. A characteristic of the PEP regime is that an improvement of the fusion reactivity over non-pellet discharges is obtained under the condition of near-equal electron and ion temperature. A maximum neutron production rate of 0.95.1016 s-1 was obtained in a double-null X-point discharge with 2.5MW of neutral beam heating and 9MW of ion cyclotron resonance heating, with central ion and electron temperatures of about of 10keV and a central deuterium density of 8.0.1019 m-3. The corresponding fusion product nD Ti τE is between 7.0 and 8.6.1020 m-3s keV. The enhanced neutron production is predominantly of thermonuclear (maxwellian) origin. The compatibility of these regimes is an important issue in the context of tokamak ignition strategies. Several technical developments on JET have played a role in the achievement of this result: first, the use of low voltage plasma breakdown (0.15V/m) in order to permit pellet injection in an X-point configuration prior to formation of a q=1 surface; second, the elimination of ICRH specific impurities with antenna Faraday screens made of solid beryllium; third, the use of a novel system of plasma radial position control that stabilises the coupling resistance of the ion cyclotron heating system.