A method was developed for the determination of boron in titanium by inductively coupled plasma mass spectrometry (ICP-MS). A commercially available PTFE sample introduction system, leading to the desired low detection limits for boron, was used. The method is suitable for the determination of boron concentrations down to about 1-mu-g g-1 in the solid material. The influence of the internal standard on the precision was studied and beryllium was selected as the internal standard. For the titanium analysed (BCR reference material 090), the ICP-MS result agreed with those obtained using other techniques. Several bars of titanium reference material were supplied and a study of the homogenity of boron in this material was made. Using analysis of variance on the results obtained for the different bars, the homogeneity of boron in the reference material could be estimated to be better than 2.1%.