The change of the permittivity Δε is measured in high electric fields E up to 107 V m–1 for n-hexane, n-heptane, cyclohexane, carbon tetrachloride, benzene, toluene and carbon disulphide at 25 °C. The effects are positive, vary linearly with E2 and do not depend on the frequency of the analysing field in the range 0.5–50 MHz. The amplitudes of the effects are similar to recent literature values, but differ when measured in cells of different design. Δε is determined from the amplitude modulation of the output voltage of a resonant circuit to which an alternating high field is applied. The effect shows dispersion with the frequency of the high field in the kHz region. From this as well as from the linear dependence of most Δε/E2 values on ε2 it is concluded that an important part of the effect is due to electrode movements. The corrected values are compatible with experimental Kerr constants. The best value for carbon disulphide is Δε/E2=(1.25 ± 0.10)× 10–19 V–2 m2.