Left testes of male mice in two groups were irradiated by the He-Ne laser with two different powers. Synaptonemal complex (SC) of spermatocytes with a surface microspreading technique were examined by the electron microscopy. No significant increase in frequency of SC aberrations was observed in the irradiated left testes of the two experiment groups. After irradiating the types of SC aberrations, involving breakage, LE breakage, asynapsis, synapsis irregularity and ring, were not radically different in the experiment groups from the control. The laser energy density for the experiment was much higher than for clinical treatment. The results show irradiating testes by He-Ne laser isn′t able to induce SC aberrations.