A genetic algorithm is developed to find the ridges in paper fingerprints. It is based on the fact that the ridges of the fingerprints are parallel. When scanning the fingerprint, line by line, the ideal noise-free gray level distribution should yield lines of black and white. The widths of these lines are not constant. The proposed genetic algorithm generates black and white lines of different widths. The widths change until we get the best match with the original fingerprint.