We present variational calculations of the one-body density matrices and momentum distributions for 3 He mixtures in the zero-temperature limit, in the framework of the correlated basis functions theory. The ground-state wave function contains two-and three-body correlations and the matrix elements are computed by ͑Fermi͒ hypernetted chain techniques. The dependence on the 3 He concentration (x 3 ) of the 4 He condensate fraction (n 0 (4) ) and of the 3 He pole strength (Z F ) is studied along the Pϭ0 isobar. At low 3 He concentrations, the computed 4 He condensate fraction is not significantly affected by the 3 He statistics. Despite the low x 3 values, Z F is found to be quite smaller than that of the corresponding pure 3 He because of the strong 3 He-4 He correlations and of the overall, large total density . A small increase of n 0 (4) along x 3 is found, which is mainly due to the decrease of with respect to the pure-4 He phase. ͓S0163-1829͑97͒03242-6͔