The use of line features in real-time visual tracking applications is commonplace when a prior map is available, but building the map while tracking in real-time is much more difficult. We describe how straight lines can be added to a monocular Extended Kalman Filter Simultaneous Mapping and Localisation (EKF SLAM) system in a manner that is both fast and which integrates easily with point features. To achieve real-time operation, we present a fast straight-line detector that hypothesises and tests straight lines connecting detected seed points. We demonstrate that the resulting system provides good camera localisation and mapping in real-time on a standard workstation, using either line features alone, or lines and points combined.