[en] The advantages of high energy cyclotrons as compared to small compact cyclotrons for the production of special radionuclides are outlined. The routine production of ¹²³I (T=13.3 h) and ²⁸Mg (T=21.1 h) by means of high energy nuclear reactions at the Julich Isochronous Cyclotron is described. The reaction ¹²⁷I(d,6n)¹²³Xe yields (in β⁺,EC) ¹²³I at 78 to 64 MeV is used for the production of ¹²³I with thick target yields of 8 mCi/μA and high radionuclidic purity. The practical experience in the application of this process, which is well suited for the production of Na¹²³I and for ¹²³Xe-exposure labelling techniques, is reported. ²⁸Mg is produced by the ²⁷Al(α,3p)²⁸Mg reaction at 140 to 30 MeV with thick target yields of 40 μCi/μAh. The carrier-free ²⁸Mg is separated from the matrix activities by coprecipitation and anion exchange with chemical yields of 80%. (author)