Michel Brion: Log homogeneous pairs Abstract : Consider a smooth complete algebraic variety X and a reduced effective divisor D on X, with normal crossings. We say that the pair (X,D) is log homogeneous if the logarithmic tangent sheaf (consisting of vector fields on X which preserve D) is generated by its global sections. The talk will discuss the structure and classification of log homogeneous pairs; they turn out to be closely related to spherical varieties.