A urine collection bag comprising - an end with an opening at the top and a closed bottom at an opposite end defining a longitudinal direction of the bag between the opening and the bottom and a transverse direction of the bag transverse to the longitudinal direction, - an inlet at the opening extending from the opening and a length into the bag, - the inlet being an anti-reflux valve in form of a foil-valve with four layers of foil welded together in the longitudinal direction defining a width of the inlet between the welds in the transverse direction and the length of the inlet as a length of the foils in the longitudinal direction, - wherein a relationship between a most narrow width of the inlet and the length of the inlet is such that the length is more than 2.5 times the width.
