complex z0

hi.
if i get a complex impedance of a microstrip trace, then what is the impedance really? the real part, or the magnitude?
for terminating a microstrip line. normally done by a resistor.

i just did some EM simulation, then calculations on the results, and it says:
z0=67.36+j*64.8 ohm. magnitude is 93.42
if i calculate the impedance with a calculator, then it says 67 ohm.