The plupose of thii letter is to give all the static, splierically symmehic perfect fluid solutions admitting a homothety. This family can be completely characterized by means of a real parameter y (arising quite naturally from the equation of state for these fluids, see below), which must be in the interval [ I , 21 in order to satisfy energy conditions. The two limiting values of y. namely y = 1 and y = 2 correspond to Minkowski flat spacetime and to the HHB solution, respectively.A few remarks concerning the similarity group and its action are in order here. It is a well known fact that an r-parameter group of homotheties H, (in which at least one proper homothety exists) always admits an (r -l)-parameter subgroup of isomehies G,-I. Now, the maximal dimension of the group of homotheties that a perfect fluid spacetime may admit is r = 7, in which case it is one of the special Robertson-Walker spacetimes [2], and therefore they are all known. The case r = 6 is not compatible with an energy-momentum tensor of the perfect-fluid type; thus, apart from the special Robertson-Waker solutions mentioned above, the highest dimension of the group of homotheties that a perfect fluid spacetime may admit is r = 5. In such case, the associated isometry subgroup Gq has necessarily three-dimensional non-null orbits