A method using multiple-collector inductively coupled plasma source mass spectrometry for the precise measurement of Ti isotope composition in natural materials has been developed. Instrumental mass discrimination is corrected using a "standard-sample bracketing" approach by expressing the isotope ratios of samples relative to those of the bracketing standard. Variations in 47Ti/46Ti, 48Ti/46Ti, 49Ti/46Ti and 50Ti/46Ti ratios of samples are expressed in ε units which are deviations in parts per 104 from the same isotope ratios of the reference material. The long-term repeatability at the 2 standard deviation level is 0.4, 0.6, 0.7 and 0.8 ε units in terms of 47Ti/46Ti, 48Ti/46Ti, 49Ti/46Ti and 50Ti/46Ti ratio measurements, respectively. The technique reported here makes it possible for the first time that both mass-dependent fractionation and isotope anomalies of Ti isotopes in natural materials can be measured to high precision. © 2002 Elsevier Science B.V. All rights reserved.