  We initiate the study of loop-level holographic correlators in the presence
of defects. We present a unitarity method which constructs loop corrections
from lower order data. As an example, we apply this method to 6d
$\mathcal{N}=(2,0)$ theories with $\frac{1}{2}$-BPS surface defects and report
the first holographic two-point function at one loop.
