  Araujo proved in his thesis \cite{A} that a $C^1$ generic surface
diffeomorphism has either infinitely many sinks (i.e. attracting periodic
orbits) or finitely many hyperbolic attractors with full Lebesgue measure
basin. The goal of this paper is to extend this result to $C^1$ vector fields
on compact connected boundaryless manifolds $M$ of dimension 3
(three-dimensional flows for short). More precisely, we shall prove that a
$C^1$ generic three-dimensional flow without singularities has either
infinitely many sinks or finitely many hyperbolic attractors with full Lebesgue
measure basin.
