To simplify the expression \( \frac{8}{\sqrt{3}} \) and rationalize the denominator, we multiply both the numerator and the denominator by \( \sqrt{3} \):
\[ \frac{8}{\sqrt{3}} \cdot \frac{\sqrt{3}}{\sqrt{3}} = \frac{8\sqrt{3}}{3} \]
Thus, the final answer, with the denominator rationalized, is:
\[ \frac{8\sqrt{3}}{3} \]