From a radial velocity study of 60 spectrograms of the binary system 68u Her, systematic velocity differences have been found to exist between the He I singlet lines and the He I triplet lines of the primary component. These differences are independent of orbital phase, date of observation or spectrograph employed and can be interpreted in terms of the existence of a large fraction of 3He in the atmosphere of the primary component. A 3He/4He ratio of between 4:1 and 49:1 is suggested.