The authors present measurements of HMTSF-TCNQ (Hexamethylenetetraselenaful-valenium-tetracyanoquinodimethanide) resistivity along the chain axis, during irradiation at 21 K with fast neutrons ( similar 1 MeV) and heavy ions ( similar 100 MeV). A defect concentration estimated to be 10** minus **3 mole fraction, increases the resistivity at 21 K by a factor of 4. These preliminary results are used to discuss the validity of two very simple radiation damage models: i) three-dimensional percolation, and ii) semi-metal irradiation.