Magnetic field exposures at railway maintenance sites were investigated. Ninety three spot magnetic field measurements were taken at five rail maintenance sites in Maryland or Pennsylvania. The sites included a three track segment in a rural area (site-A), a four track segment in an urban industrial area (site-B), a large station in an urban area (site-C), an urban power substation (site- D), and a six track segment in an urban area (site-E). A Multiwave- II system which measured 25, 60, and 100 hertz (Hz) magnetic fields was used. The recorded waveforms were examined to identify the different frequencies within the waveforms. Multiwave-II measurements were supplemented with personal monitoring using an Emdex personal dosimeter worn by the measurer. Typical work performed at the sites included rail removal and replacement, leveling ballast under the ties, and rebuilding a substation transformer. Magnetic fields measured at 25Hz, main frequency of rail current near the worksites, with the Multiwave-II system varied from 1.5 to 185 milligauss (mG). The lowest field was at site-C and highest near a transformer at site-A. The median root mean squared (rms) 25Hz magnetic fields measured at site-A, site-B, site-C, site- D, and site-E were 16.7, 22.3, 6.54, 40.3, and 16.7mG, respectively. The fields contained frequency components varying from 40 to 1,000Hz. The median rms 25Hz magnetic fields measured at site-A, site-B, site-C, site-D, and site-E with the Emdex monitor were 18.2, 7.3, 2.6, 6.6, and 12.6mG, respectively. The rms magnetic fields measured at 60 and 100Hz with the Multiwave-II were lower than the 25Hz fields, with medians from 0.62 to 8.9 and 0.18 to 0.96mG, respectively. Time weighted average personal (TWA) exposures estimated by combining the spot measurements with the time workers spent at each site varied from 3.0 to 18mG, depending on the specific site and how often trains passed. The authors conclude that the TWA magnetic field exposures of railway workers is higher than those of other workers but comparable to electric utility workers.