The isotropy of faint radio sources has been investigated by applying Scheuer's statistical method to the interferometer records of the 4C survey in the declination range – 07° to + 80°. There is no evidence of anisotropy in the distribution of sources having flux densities greater than 0.2 × 10 −26 w.m −2 Hz −1 at 178 MHz. It is concluded that this observation renders the ‘local origin’ hypothesis of quasi-stellar sources highly improbable. In evolutionary cosmologies the Universe is isotropic on a large scale to a redshift z ≈ 4.