For a graph $G$, let $\mathbb{D}(G)$ denote the set of all strong orientations of $G$, and the oriented diameter of $G$ is $f(G)=\min \{diam(D) \mid D \in \mathbb{D}(G)\}$, which is the minimum value of the diameters $diam(D)$ where $D \in \mathbb{D}(G)$. In this paper, we determine the oriented diameter of complete tripartite graphs $K(3,3, q)$ and $K(3,4, q)$, these are special cases that arise in determining the oriented diameter of $K(3, p, q)$.