We present first-principles calculation for the behavior of antimony telluride under stress. We focus on the calculation of transport properties for pure Sb2Te3 and the investigation of stress-induced defects. Our transport calculations were done within first-principles using the linearized-augmented plane-wave method, where we first calculated the transport distribution for several stress conditions. Next, using these stress dependent transport distributions, we derived the stress dependence of the electrical conductivity, the Seebeck coefficient, and the power factor. Our calculations for the stress-induced defects were done utilizing a pseu-dopotential method and confining ourselves to the antisite defect. In all cases, our results are in good agreement with experimentally obtained data. Furthermore, we found that hydrostatic pressure does not improve the power factor, while, on the other hand, a large increase under uniaxial stress can be observed. Also, both hydrostatic pressure and uniaxial stress are found to lower the formation energies of the antisite defects, suggesting a structural transition at high pressures.