SUMMARYParallel discrete direct and adjoint sensitivity analysis capabilities are developed for arbitrary Mach flows on mixed-element unstructured grids. The discrete direct and adjoint methods need a consistent and complete linearization of the flow-solver to obtain accurate derivatives. The discontinuous nature of the commonly used unstructured flux-limiters, like Barth-Jespersen and Venkatakrishnan, make them unsuitable for sensitivity analysis. A modification is proposed to make these limiters piecewise continuous and numerically differentiable, without compromising the monotonicity conditions. An improved version of Symmetric Gauss-Seidel that significantly reduces the computational cost is implemented. A distributed-memory message passing model is employed for the parallelization of sensitivity analysis solver. These algorithms are implemented within a three-dimensional unstructured grid framework and results are presented for inviscid, laminar and turbulent flows.