Santutxu (it can also be spelled as Santuchu when written in Spanish) is one of the most populous neighbourhoods of Bilbao (Basque Country). It belongs to the 4th urban district, named Begoña. It is basically a popular residential neighbourhood but has also a relatively strong commercial area, including a food retail market of its own.
Santutxu is the most densely populated neighbourhood of Bilbao and Europe, at 41,430 hab/km2. 
There are two underground stations (Metro Bilbao) in Santutxu, called 'Santutxu' (in Karmelo St. & Zabalbide St.) and 'Basarrate' (in Basarrateko Landa).