Pollardstown Fen, Nature reserve and Special Area of Conservation in County Kildare, Ireland.

Pollardstown Fen is Ireland's largest extant calcareous spring-fed fen, about 321 acres (1.3 km2) in County Kildare, fed by petrifying springs from the Curragh aquifer. Its flora is dominated by black bog rush and saw sedge, with fly orchid, western bladderwort, sphagnum moss and broad-leaved bog cotton also recorded. A boardwalk crosses the site for visitors.

Pollardstown Fen was designated a national nature reserve in 1986, partly in response to drainage schemes from the 1960s that converted parts of the fen to agricultural land. In 1990 it was declared Ramsar site number 474. The Irish state owns 60% of the fen. Water levels were disrupted for a time by construction of the Kildare bypass in 2003.

The Irish name is Eanach Bhaile Pholaird, meaning the fen of Pollard's town. The state owns about 60% of the site, and a boardwalk lets visitors cross the wet ground. The reserve was declared Ramsar site number 474 in 1990.

A boardwalk crosses the fen for visitors, keeping walkers above the wet ground. The reserve lies near the Curragh in County Kildare, and water levels here were disturbed for a time by construction of the Kildare by-pass in 2003, so some sections may remain wetter. Stay on the boardwalk and marked paths.

The fen's petrifying springs deposit calcium carbonate, and three rare Vertigo whorl snails live here: Vertigo geyeri, Vertigo angustior and Vertigo moulinsiana. The site was declared Ramsar site number 474 in 1990.