The eastern massasauga, Sistrurus c. catenatus, is a small rattlesnake threatened with extirpation throughout its range. Massasaugas occur in a variety of habitats and adequate knowledge of their natural history at local scales is essential for effective management. We used radiotelemetry to document patterns of movement and macrohabitat selection of massasaugas in a fen environment, an important, but understudied, habitat. Based on both 100% minimum convex polygons and 95% kernel density, seasonal home ranges of males were larger than those of nongravid females which, in turn, were larger than those of gravid females. Activity center estimations followed the same trend as the seasonal range estimations. Similarly, activity centers (50% kernel density) of males were larger than those of nongravid females which were larger than those of gravid females. Nongravid females and gravid females differed in their mean frequency of daily movement, distance moved per day and total distance moved in a season. Males also differed from gravid females in these three regards, but only differed from nongravid females in distance moved per day. Compositional analysis of both 100% MCPs and 95% kernel densities indicated a preference for emergent wetland vegetation by all individuals; however, wooded areas and meadows were used to a lesser extent.