Antimony and nitrogen have been implanted at room temperature in type Ia diamonds. From the EPR spectrum we can deduce that for small implantation doses isolated broken bonds are created. Multiple defects are created for implantation dosesD(Sb) = 2–5×1013ions/cm2andD(N) = 5×1014ions/cm2. For higher implantation doses single broken bonds prevail. Complete graphitization is obtained for high doses:D(Sb)⩾5×1015ions/cm2andD(N)⩾1016ions/cm2. In antimony doped diamonds the conductivity is only due to defects.