The paper reports on extensive 3 He vapour-pressure measurements carried out at PTB. To investigate in detail the main error sources, three different types of vapour-pressure cells and three different arrangements of pressuresensing tubes were used. In the temperature range from 0.65 K to 1.2 K, the repeatability of the realisation of 3 He vapour-pressure temperatures T 90 according to the International Temperature Scale of 1990, ITS-90, over eight runs was of order of 0.12 mK, whereas the repeatability over four runs using one and the same, optimised cryogenic set-up was of order of 0.03 mK. Below 1 K, the T 90 realisation is compared to data available in the literature via wire scales.