The neutron transmission of 99Tc for neutron energies less than 1 keV has been measured with the Material Testing Reactor (MTR) fast chopper with a resolution of 0.04 to 1.8 µsec/meter. A total neutron cross section at 0.0253 eV of 24.7 ± 1.7 b was obtained. To fit the cross-section data in the thermal energy range, it was necessary to assume a contribution by a bound level together with contributions from measured resonances at positive energies. Resonance parameters are presented for levels observed in the energy region from 0.01 to 300 eV. Two additional resonances, not listed in the literature, have been measured and analyzed. Parameters of individual resonances below 300 eV and average parameters at higher energies, give a resonance absorption integral of 340 ± 20 b, and a value of (0.43 ± 0.14) × 10−4 for the s-wave neutron strength function.