The Rusty-breasted Cuckoo (Cacomantis sepulcralis) is a species of cuckoo in the Cuculidae family. It is found in Indonesia, Malaysia, the Philippines, Singapore, and Thailand. Its natural habitat is subtropical or tropical moist lowland forests.
In Singapore, it is an uncommon breeding resident.
It has a typical morph and a hepatic morph. The typical morph has a grey upper body, and orange lower body. The hepatic morph has rufous upperparts and pale underparts, both with dark bars. The juvenile looks like hepatic morph.
The confusion species in Singapore is the Plaintive Cuckoo, which lacks the yellow eye-ring.