To simplify the expression \(\frac{13^{11}}{13^{-8}}\), we can use the properties of exponents. Specifically, we can apply the rule:
\[ \frac{a^m}{a^n} = a^{m-n} \]
In this case, we have:
\[ m = 11 \quad \text{and} \quad n = -8 \]
So we can simplify the expression as follows:
\[ \frac{13^{11}}{13^{-8}} = 13^{11 - (-8)} = 13^{11 + 8} = 13^{19} \]
Thus, the simplified expression is:
\[ \boxed{13^{19}} \]