Abstract: Reindeer and caribou are terrestrial herbivores, that feed on lichens and are used for commericial and subsistence food products. Caribou are a key component of the arctic food web and the biaccumulation of toxic contaminates, such as Mercury (Hg), needs to be monitored to establish a baseline as the arctic enviroment is impacted by both climate change and future industrial development. A changing climate in Alaska is influencing plant species composition, fire regime, melting and flooding events, and thus, impacting Hg bioavailabilty in the food chain. Industrial development in Asia is also projected to increase the stmospheric global pool of Hg from increased coal combustion. Reindeer, a domesticated representative of caribou, can be used as as terrestrial biomonitor for metal exposure. In this study total mercury concentrations were measured in lichens and in hair of grazing reindeer on defined ranges across Alaska to establish a basseline for futere hypothesis development and testing regarding Hg deposition. The Hg mean level for Seward Peninsul lichens on the Davis Range was 37.4 ng ḡ¹, on the Gray Range 47.1 ng ḡ¹, on the Kakaruk Range 42.2 ng ḡ¹, and 41.7 ng ḡ¹ on the Noyakuk Range. Lichen Hg levels on St. Lawrence Island was 46.6 ng ḡ¹. Methyl mercury levels in lichens were found to be below detection levels. Reindeer grazing on these Ranges had mean Hg hair levels of 14.6 ng ḡ¹ (Davis herd), 83.4 ng ḡ¹ (Gray herd), 40.3 ng ḡ¹ (Noyakuk herd). Two reindeer on St. Lawrence Island had an average of Hg of 43.0 ng ḡ¹. Sample size ranged from n=2 to n=11. Hg mean levels in lichen on Seward Peninsula were higher than Hg means of two ranges in Northern Mongolia. The Hg levels observed in this study indicate that Hg levels in Alaska are low at this time and pose no risk to the health of reindeer or human subsistence harvesters. A significant relationship between Hg in lichens on the ranges and the Hg in reindeer on those ranges has not been established. There are insufficient data on Hg levels in many areas of the north and more information is needed on location specific and time trends in Hg concentrations. Lichens and reindeer hair provide a good, non-invasive method of monitoring metal exposure changes in Alaskan ecosystems.