In practical design, frames are assumed to be connected either by rigid or pinned joints. Strictly speaking, all joints are semi-rigid, so this assumption does not normally represent the actual behaviour of a realistic steel frame. Due to extensive research into the behaviour of frames with semi-rigid connections and the availability of low-priced personal computers, the idealized pinned or rigid joint assumption for the simplified analysis of a steel structure may not be necessary or justifiable. So far, most research on the subject has concentrated on the static linear and nonlinear analysis of flexibly jointed steel frames. The dynamic behaviour of steel structures with semi-rigid joints has not been extensively investigated. The response of a steel frame will be of interest to the designer for the purpose of ensuring the safety and serviceability of the structure under the action of dynamic loads. This paper is addressed to the extension of the well known stiffness matrix method of analysis for framed structures to cover a more general case of vibration and stability analysis of flexibly connected steel frames.