In this floristic study, four species of Passiflora (Passiflora cincinnata, P. foetida, P. misera, P. subrotunda) were recorded in the coastal region of the Brazilian State of Piauí. The taxa occur in habitats with moist, muddy, sandy and stony substrates. The most prevalent species were P. foetida and P. subrotunda. An identification key is provided, together with descriptions of the species and data on their occurrence and distribution in the study region.