Three incidental sightings of the flat-headed cat Pnonailurus planiceps, a little-known species, were made in south-east Sumatra. Sightings were on lowland floodplains in two distinct habitats, primary peat swamp forest and secondary lowland forest, the latter suggesting some tolerance to modified habitats. Sightings were along or near waterways. A dead adult male found in Berbak National Park is the first confirmed record for the park. Morphometrics of this individual were consistent with other published measurements for the species. Museum specimens indicate a wide historic distribution in south-east Sumatra. Recent information confirms the species's presence in protected areas of eastern, southern and western Sumatra, although this is mostly limited to presence/absence data, and the conservation status and habitat requirements of the species in south-east Sumatra are unknown. Regional degradation of riparian habitats and the isolation of protected areas warrant concern for the conservation status of the species.