Aalsum () is a small hamlet in the Dutch province of Groningen. It is located in the municipality of Westerkwartier, about 1.5 km west of Oldehove.
The hamlet was located on a wierde, an artificial dwelling hill. The hill was partially excavated in the 20th century; a bow from the ninth century was found. Plans to reconstruct the hill were canceled.
According to the 19th-century historian A.J. van der Aa, Aalsum had 80 inhabitants in the middle of the 19th century; presumably, this includes the surrounding countryside.