we present records of two caprimulgid species hitherto unreported for argentina: the lesser nighthawk (chordeiles acutipennis), and the spot-tailed nightjar (caprimulgus maculicaudus). the genus caprimulgus would thus be represented by five species in argentina, and the genus chordeiles by three. chordeiles acutipennis was observed (without formal evidence) in the provinces of salta, chaco and formosa, and caprimulgus maculicaudus was observed and tape-recorded in misiones province. we discuss fieldmarks of chordeiles acutipennis. we provide other observations and records of both species in paraguay, where chordeiles acutipennis is considered hypothetical, and also describe the display of caprimulgus maculicaudus in detail.