The safety of the Mirror Advanced Reactor Study (MARS) tandem mirror reactor is assessed. Only prompt consequences to the public at the plant boundary, which is taken to be 1000 m, are considered. The major radioactive inventories in MARS reside in the first-wall/blanket structure, coolant, and tritium. The greatest radioactivity resides in the HT-9 first-wall/blanket structure. The only accident scenario identified that could lead to a first-wall meltdown was a loss-of-coolant accident (LOCA) accompanied by the inability to shut off the plasma. However, since only oxides of molybdenum are expected to be volatized from the hot HT-9 structure, the public consequences are found to be low. A LOCA can result in large doses if the activity in the activated corrosion products and LiPb coolant can be transported outside the reactor containment building. However, most of the LiPb would be expected to solidify, and any aerosols that are produced will likely plate out on surfaces or settle. Various tritium accident scenarios were considered. Release of all the tritium in the reactor building (51 g) leads to a dose of 21 rem. A much more likely accident involves partial leakage due to some reactor containment damage.