This note describes the recent trend and the pattern of trade between South Sudan and Uganda, which showed a dramatic growth initially but remains vulnerable to changing local security conditions. It analyzes how crossborder trade is still costly for South Sudan due to several key constraints at the border as well as behind the border. Customs processing in South Sudan remains cumbersome largely due to weak staff capacity and inefficiency in customs administration. Poor road quality and numerous roadblocks and informal payments between border posts and Juba drive up the trading cost further. The current trade pattern between the two economies is highly asymmetrical—the rapid growth comes solely from a skyrocketing increase in Ugandan exports to South Sudan. It is also largely informal, where women play significant roles and sensitive to local security conditions. Even with the recent growth in trade, physical and institutional constraints in trading are still substantial and addressing those issues would further enhance trading opportunities for South Sudan with its neighbors and sustain its trade ties with them.