In this paper, we present an adaptive output feedback controller using feedthrough components. This controller consists of an observer-based baseline controller with integral action and a closed-loop reference model and is shown to stabilize a class of linear plants with uncertain parameters including nonzero feedthrough matrices. The presence of direct feedthrough is addressed through the use of suitable feedback gains in the closed-loop reference model. The performance of the adaptive controller is illustrated using simulation studies of a model of an agile aircraft. The results show that a better performance with improved robustness can be obtained with the proposed adaptive controller. These results have important implications on aircraft problems where acceleration measurements are available.