This paper presents an analysis of a number of problems related to the auspices and the imperium of Roman magistrates and promagistrates. The first part concerns prorogued magistrates and confirms that, despite the lack of the auspicia urbana after the expiration of their annual magistracy, their power outside Rome was still considered valid, since it was founded on the auspices of departure that they had taken within the city during the consulate or the praetorship. Moreover, this fact caused that outside the city no clear hierarchy could exist between a consul and a proconsul, as shown by many examples. Still, some conservative senators would consider these promagistrates as private persons, since they could not act within the limits of the city. The second part examines some cases when the Roman popular assemblies elevated a lesser imperium to a higher degree. Then the validity of the auspices of the so called priuati cum imperio is discussed. These promagistrates too validated their military imperium with an auspication, but this was taken outside the city since they had no power within the pomerium. This analysis leads to refute the statements about the invalidity of the promagisterial auspices contained in two passages of Cicero (div. 2, 77 and nat. deor. 2, 9) and then to reconsider the whole case of the subordination of the proconsul of Africa Cossus Cornelius Lentulus to the auspices of the emperor Augustus in AD 7–8 (IRT 301). This was due to a voluntary act justified by the serious military crisis of those years and not to a permanent lack of the auspices by the proconsuls, as some scholars argue. A final note explores the particular and unprecedented auspical position of Augustus inside the city after 19 BC.< Réduire