The source counts derived from the fourth Cambridge catalogue of radio sources (4C) are presented and are combined with previously published results to give the number/flux density (log N/log S) curve over the range of flux density 0.27 < S < 35 × 10−26(c/s)−1. The correction necessary to take account of confusion is deterrnined by a Monte Carlo process and the corrections for angular diameters of sources and source clustering are also discussed. On the assumption that the form of the source counts can be explained by density variation with epoch, forms of this density variation are derived which would be consistent with the latest derivation of the luminosity distribution function.