The problem of decentralized adaptive output tracking control of a class of interconnected stochastic nonlinear systems is considered. In the control design, decentralized state observers and backstepping techniques are applied. To eliminate the influences of interactions with other subsystems, a differentiable function is employed. It is shown that the designed local adaptive controllers can ensure that all the signals in the closedloop system are bounded in probability. Furthermore, the tracking errors can be limited to a small residual set around the origin in the fourth moment sense and can be adjusted by choosing suitable design parameters. The problem of decentralized adaptive output tracking control of a class of interconnected stochastic nonlinear systems is considered. In the control design, decentralized state observers and backstepping techniques are applied. To eliminate the influences of interactions with other subsystems, a differentiable function is employed. It. The illustrated errors can be limited to a small residual set around the origin in the fourth moment sense and can be adjusted by choosing suitable design parameters.