The perimeter of an equilateral triangle can be calculated by multiplying the length of one side by 3, since all sides are equal in length.
For an equilateral triangle with a side length of 5 cm, the perimeter can be calculated as follows:
\[ \text{Perimeter} = 3 \times \text{side length} = 3 \times 5 , \text{cm} = 15 , \text{cm} \]
Therefore, the perimeter of the equilateral triangle is \( 15 , \text{cm} \).