To simplify the expression \(3^8 \cdot 3^3\) using the Product Rule of Exponents, we can apply the rule which states that when multiplying two powers that have the same base, we add the exponents.
Here's the step-by-step simplification:
\[ 3^8 \cdot 3^3 = 3^{8+3} \]
Now, add the exponents:
\[ 3^{8+3} = 3^{11} \]
So, the simplified expression is:
\[ 3^{11} \]