Geochemical drainage reconnaissance by stream sediment sampling yielded pronounced anomalies in the vicinity of areas which have been prove to contain disseminated copper sulphides. The results showed considerable variation in the ratio of total to cold-extractable copper in the anomalous stream sediments. These variations were found to be related to the pH of the stream waters, which ranged from 3.5 to 8.5. In these circumstances it is necessary to analyse the sample for both total and cold-extractable metal and to take into account the pH of the stream water when interpreting the geochemical data.