A new determination of the relative orbit of Sirius has been conducted, in support of an ongoing sequence of Hubble Space Telescope observations. The last major determination of the relative Sirius A/B orbit was that of van den Bos (1960). The van den Bos investigation included all visual observations up to 1960. The present analysis incorporates all post-1960 visual observations as well as a substantial set of published photographic observations, from the Bosscha Observatory and the US Naval Observatory, covering three decades prior to 1986. Additionally, the observations of the apparent orbit of Sirius A about the system barycenter (Gatewood & Gatewood 1978) are reevaluated with respect the new relative orbit. A combination of these data sets is used to establish an improved and updated orbit for Sirius as well as the astrometric masses of the two components. This work was supported in part by STScI grant GO-9334.