The recent elucidation of the three-dimensional structure of gelsolin segment 1 and profilin provides new insights on how these proteins recognize actin. Although the picture is still incomplete and not all biochemical data are consolidated, the results offer clues on how these proteins exert their effect on actin and how they may modulate the cytoskeleton dynamics. Binding studies on the villin head piece, thymosin beta 4 and mutants of both peptides allowed to identify critical residues important for actin binding and give the first picture of new actin binding interfaces. The interface of the modelled actomyosin complex is also briefly discussed.