Cambodia supports populations of three Critically Endangered vulture species that are believed to have become isolated from the rest of the species’ global range. Until recently Cambodia’s vulture populations had remained stable. However a recent spike in the number of reports of the use of poisons in hunting practices suggests the need to re-evaluate the conservation situation in Cambodia. Population trend analysis showed that since 2010 populations of the White-rumped Vulture Gyps bengalensis and Red-headed Vulture Sarcogyps calvus have declined, while the Slender-billed Vulture Gyps tenuirostris may also have started to decline since 2013. These trends are supported by evidence of reduced nesting success. A survey of veterinary drug availability revealed that diclofenac, the non-steroid anti-inflammatory drug responsible for vulture declines in South Asia was not available for sale in any of the 74 pharmacies surveyed. However, a poisoned Slender-billed Vulture tested positive for carbofuran in toxicology tests. This provides the first evidence of a vulture mortality resulting from carbofuran in Cambodia. The findings suggest the urgent need to tackle use of carbamate pesticides in hunting. Proposed conservation actions are: a) prevention of poisoning through national bans on harmful carbamate pesticides and diclofenac and education campaigns to reduce demand and use; b) training of personnel in priority protected areas in detection and response to poisoning incidents; c) maintenance of a safe and reliable food source through vulture restaurants to ensure short-term survival, and d) protection and restoration of large areas of deciduous dipterocarp forests to enable long-term species recovery.