Microcrystals of cubic boron nitride powders synthesised under dierent conditions and further irradiated with neutrons and electrons have been investigated. It was found that some changes of the samples' paramagnetic properties depend on the electron irradiation dose. It was also shown that the initial boron type defects growth occurs under thermal neutron, as well as under fast neutrons irradiation. The nitrogen-containing defects concentration changes in a threshold manner.