A simple, semi-automated method for the analysis of calcium and phosphorus in small volumes of human milk is described. Samples are ashed, digested with dilute hydrochloric acid and assayed with commercially available kits on a centrifugal analyser. The precision and accuracy of the method are similar to those of standard manual methods using larger volumes of milk. Analysis of human milk for phosphorus without prior ashing and digestion gives observed concentrations only 30-40% of their true value.