In this work we present the design, numerical and experimental results for an ultrathin Soret fishnet metamaterial lens working at fexp = 96.45 GHz. The fishnet metamaterial with effective refractive index close to zero (n = -0.06) is introduced on the back side of the classical Soret lens in order to improve its efficiency. The experimental results are in good agreement with simulation results and demonstrate half-wavelength focal length and spot size. In a lens antenna configuration a high gain of 10.64 dB was measured at the operation frequency. The presented lens has a low-cost compact design, and may find applications in integrated lens antenna systems.