  Let $K$ be an imaginary quadratic field and $ \mathcal{O}_K$ be its ring of
integers. A set $\{a_1, a_2, \cdots,a_m\} \subset \mathcal{O}_K\setminus\{0\}$
is called a Diophantine $m$-tuple in $\mathcal{O}_K$ with $D(-1)$ if $a_ia_j -1
= x_{ij}^2$, where $x_{ij} \in \mathcal{O}_K$ for all $i,j$ such that $1 \leq i
< j \leq m$. Here we prove the non-existence of Diophantine $m$-tuples in
$\mathcal{O}_K$ with $D(-1)$ for $m > 36$.
