  We study parametric amplification in nonlinear left-handed transmission
lines, which serve as model systems for nonlinear negative index metamaterials.
We experimentally demonstrate amplification of a weak pump signal in three
regimes: with the signal in the left-handed band, with the signal in the stop
band, and with the signal at a defect frequency. In particular, we demonstrate
the amplification of the incident wave by up to 15dB in the left-handed regime.
