Armenian vipers (Montivipera raddei) have a restricted and fragmented distribution throughout portions of Armenia, eastern Turkey, and northwestern Iran. Over the past 40 years their population numbers have dropped by nearly 88% due to a combination of over-collection for the pet trade, conversion of habitat to agriculture, and overgrazing by livestock. While a few studies have examined aspects of their reproductive biology, we know very little about the spatial ecology of this species. We used radiotelemetry to study the spatial ecology and habitat use of Armenian vipers inhabiting a landscape modified by human use in Kotayk Province, Armenia during the spring 2007–2009 (17 males, 11 females) and for complete active seasons 2008–2009 (8 males, 6 females). We found no significant difference between sexes for home range size, average movements, or movement rates through areas involving cropland versus strictly steppe. Home ranges were significantly larger for males whose spring core area included some cropland. Both sexes showed significant preference for mountain steppe over cropland. Despite these differences, the interspersing of cropland among steppe habitat does not appear to impede the snakes' movements and seasonal use of the available habitat. While conservation of intact mountain steppe habitat is the ultimate goal, providing corridors of habitat in areas of agricultural development should be considered a high priority for managing this viper population into the future.