The nuclear quadrupole interaction at l87 W(/T) l87 Re was determined by time differential perturbed angular correlation inWC, WS 2 , WSe 2 , WSi 2 , and CaW0 4 to be (at 300 K): v Q = 335.9(2), 1094.9(1), 1031.6( 1), 1131,5( 1), and 1085.9( 1) MHz, respectively. The asymmetry parameter 77 was zero in all cases. For WSe 2 and CaW0 4 the temperature dependence of the nculear quadrupole interaction was determined between 300 K and about 900 K. Ab initio calculations of electric field gradients, using the WIEN95-code, were carried out for WC, WS 2 , WSe 2 , and WSi 2 at W-sites and Re-impurities, and for CaW0 4 at W-sites. Good agreement with experimental data was found.