A sensitive spectrophotometric method is described for the detection of low cyanide levels in wastewaters. Wastewaters often contain sulphide and addition of lead carbonate is the recommended method for removal of sulphide interference. However, we have found that addition of lead carbonate is unsatisfactory. The addition of a stoicheiometric amount of lead to remove the sulphide interference, this amount being determined by titration with lead acetate using a redox electrode for end-point determination, is more satisfactory. The precision and recoveries (average 91%) obtained with this modified procedure were acceptable.