New results of dielectric spectroscopy in semicrystalline nylon-6 samples with different moisture contents are presented by using a wide frequency (10(-2)-3 x 10(6) Hz) and temperature range (133-433 K). The dielectric absorption spectra in frequency domain are decomposed in Cole-Cole distributions corresponding to the local y and modes, two segmental a modes, and a high-intensity Maxwell-Wagner-Sillars relaxation. The presence of two segmental relaxations in the isothermal runs, attributed to the plasticized and the unplasticized a mode, is interpreted as the manifestation of two different length and time scales of cooperative motions. A quantitative comparison between the results obtained for the wet and dry samples, such as relaxation times variation, activation energies, Vogel-Tammann-Fulcher parameters, dielectric increments, and distribution widths, is presented for each mode and shows how the progressive drying of the sample during the experiment affects all these quantities.