Abstract. The hyperfine structure (hfs) of 181Ta has been investigated using laser radio-frequency double resonance and high resolution laser spectroscopy on collimated atomic beams. The magnetic dipole and electric quadrupole hyperfine structure coupling constants of the 5d 4 6s 6D3/.2,5/2,7/2,9/2 metastable states have been determined using radio-frequency spectroscopy. In the 5d 4 6s 6D1/2 metastable state and the excited 5d 3 6S 6p 4D3/2, 695/2 9/2 as well as the unidentified 28 182.6 cm -1 and 30021~2 cm -1 states, hfs constants have been obtained from high resolution laser spectroscopy. A radiofrequency converter has been developed in order to reach the frequency region 2.7-10 GHz.