Arrast-Larrebieu is located in the
former province of
Soule some 12 km east by south-east of
Saint-Palais and 10 km north by north-east of
Mauléon-Licharre. Access to the commune is by the D243 road which branches off the D11 west of the commune and north of
Espès-Undurein and passes through the village before continuing north-east to join the D115. The D135 from the D11 in the west to
Moncayolle-Larrory-Mendibieu in the south-east passes through the south of the commune and the hamlet of Larrebieu. The commune is mainly farmland with many forests scattered throughout the commune. The
Laxubie rises in the south of the commune and flows north past the village gathering many tributaries and joins the
Apaure north of the commune. Several small streams rise in the west of the commune and flow west to join the
Saison. ==Toponymy==