The small Caribbean island of Montserrat has been battered by several hurricanes, and beginning in 1995, pyroclastic eruptions from the Soufriere Hills Volcano have destroyed the southern portion of the island. In addition to being incinerated by pyroclastic flows (300 °C), the bats of Montserrat also have had to contend with acid rain and the deposition of volcanic ash on leaves, fruits, and flowers and its subsequent ingestion by the bats. We document a dramatic decrease in the bat population and increases in several sublethal pathologies associated with the accumulation of ash across the island coincident with the onset of volcanic activity. Before 1995, less than 1% of the fruit bats exhibited evidence of unusual tooth wear. Since 1995, fruit bats have exhibited abnormal tooth wear advanced by the ingestion of volcanic ash while feeding and grooming. Damage to the teeth often includes ablation of the entire enamel crown and the exposure of the pulp cavity. Idiopathic hair loss was practically nonexistent before 1997 but alopecia has been frequently recorded since that time in adult frugivorous bats that live within the most damaged habitats on the island. This baldness is most likely related to physiological stress, high ectoparasite loads, or possible mineral deficiencies associated with the ingestion of ash. Furthermore, we have found evidence for respiratory pathologies in Artibeus jamaicensis resulting from the inhalation of volcanic dust and ash.