Oilarandoi, Mountain summit in Pyrenees, France.

Oilarandoi is a 933-metre summit in the Adartza range of the Basque Pyrenees, within the commune of Saint-Étienne-de-Baïgorry. It is the third-lowest peak of the chain, after Madaria and Munhogain. A chapel and an orientation table stand on the grassy top, reached by a clean slope from the Ahartza pass.

The mountain connects to ancient pathways that served as traditional passages between French and Spanish territories. These historic routes continue to shape the trail networks found on the slopes today.

The mountain is a favourite among the people of Baïgorry, who treat its summit as a lookout over the region. A well-known pilgrimage is held there every Whit Monday, and a small plaque in the chapel tells the hermitage's story in French. Locals pronounce the name "Oilandoi", a form sometimes also written.

A drivable track from Baigorri circles the mountain past the Ahartza pass, and the GR-10 long-distance path helps along the way. From the pass the grassy summit lies to the north; a variant of the GR-10 climbs to it directly from the northern pass, so reaching the Ahartza pass is not required. A path from Germieta joins the GR-10 route at the pass.

The summit holds a small chapel with a plaque, written in French, recounting its history; it was opened on 25 May 1942 through the initiative of Jean Olagarai, rector of Baigorri, and restored in 1985 under Pierre Zarzabal. A pilgrimage is held here on Whit Monday.