Using as a reference the single-phase fast-decoupled algorithm, this paper describes the modifications required to produce an efficient three-phase fast-decoupled load flow. The compound-coil concept is used in the representation of power-system components, and the effect of automatic voltage regulators is modelled as part of the reactive-power Jacobian-matrix equation. It is shown that the three-phase modified fast-decoupled load flow displays all the characteristics of the original single-phase version.