With two techniques the defect complexes are studied when formed after implantation of 5 to 100 keV metal ions into tungsten. Perturbed Angular Correlation (PAC) studies clearly indicate the presence of substitutional impurities in samples implanted with Ag or In. With Thermal Helium Desorption Spectrometry (THDS), however, virtually no substitutional implants (Ag, Cu, Mn, Cr, In) could be seen after implantation due to the nearby vacancies. Migration of vacancies towards the implants during annealing at stage III temperature was observed by means of PAC measurements. At upper stage III vacancy-implant complexes disintegrate, while the substitutional fraction increases. According to THDS, no vacancy-implant complexes are left in the case of 5 keV implantation after annealing to temperatures slightly beyond stage III temperature. In the case of 20 keV implantation a vacancy-type defect is formed which is stable up to 1350 K. The results of both techniques are compared with each other and with model calculations.