  In this letter, the possible appearance of N=2 supersymmetry at a low energy
scale is investigated in the context of unified theories. Introducing mirror
particles for all the gauge and matter multiplets of the Minimal Supersymmetric
extension of the Standard Model (MSSM), the measured values of sin^2 \theta_W
and \alpha_3(M_Z) indicate that the N=2 threshold scale M_{S_2} cannot be lower
than \sim 10^{14}GeV. If the U(1) normalization coefficient k is treated as a
free parameter, M_{S_2} can be as low as 10^9 GeV. On the other hand, if mirror
quarks and leptons are absent and a non-standard value for k is used, N=2
supersymmetry breaking could in principle occur at the electroweak scale.
