We analyze the performance of two-pump fiber optical parametric amplifiers (2P-FOPA) as preamplifiers for wavelength division multiplexing transmission systems. We simulate the propagation of 10 Gb/s x 64 channels over 120 km of non-zero dispersion shifted fiber and amplify them by a 2P-FOPA before detection. We demonstrate that a careful design-of the FOPA parameters leads to high system performance, comparable than those obtained with erbium and Raman amplifiers. For signal powers of -32.5 dBm at the FOPA input we observe clear eye openings for all the amplified signal lasers, with an average gain of 22 dB and low ripple (6 dB) over 25 nm bandwidth. We study the influence of fluctuations of the zero dispersion wavelength of the FOPA fiber. These fluctuations in realistic fibers tend to reduce the average gain and degrade the noise figure and spectral gain ripple. (C) 2003 Elsevier Science B.V. All rights reserved.21841794303310