In Traditional Chinese Medicine (TCM) the Five Elements school of thought applies the elements to the Zang-Fu organs and their associated Acupuncture meridians. There is also a classification of points on each meridian that is further associated with an element, and are some of the most commonly used points.

When a pattern diagnosis is given the acupuncture treatment is then applied to balancing the organs/elements through the use of the Sheng/Ke Cycles. The Sheng Cycle illustrates how each element nourishes another, while the Ke Cycle denotes the restraining/tempering action of each element on another.

This is a very simplified example: A pattern presents as a Kidney vacuity. Kidney is associated with the element of Water. In the Sheng cycle Water is nourished by Metal (Lung), while Water nourishes Wood (Liver). So the acupuncturist might choose to insert needles in the following:

~Earth nourishes Water, so we might needle the Earth Point of the Lung Meridian to nourish Metal (which nourishes Water).
~Metal Pt of the Kidney Meridian to further nourish Water.
~Metal Pt of the Liver Meridian to sedate Wood, as Metal controls Wood in the Ke Cycle (so Metal does not draw on the Water element too strongly).

Keep in mind Five Element Theory is not the only way in which Acupuncture is applied.
References :
Certified Acupuncturist