A kinetic real-space renormalization-group approach to the shortest-path aggregation (SPA) is presented. The fractal dimension (Df) and a set of hierarchical dimensions D(q) are computed for the SPA cluster on the square lattice. In particular, 2X2 and 3 X 3 cell real-space renormalization groups have been carried out. We find Df = Fig. 1.In the lattice-bond version of the SPA, using the KRG approach of Wang et ai. , we thus distinguish between three types of bonds at each order n of the transformation: bulk bonds representing the particles on the cluster with mass M"(bold lines in Fig. 1); perimeter bonds with mass m"(wavy lines), representing the surface of the aggregate on which the next potential growth may occur; and massless empty bonds for the rest (thin lines).A cluster grows by changing perimeter bonds to bulk bonds one by one according to probabilities which are determined by the growth mechanism. As a particle is added to the cluster one perimeter bond turns into a bulk bond and all its unoccupied neighbors become growth bonds. The following rules guide the transformation: If the cell is connected from top to bottom by bulk bonds it will be renormalized into a bulk bond; if the cell is completely empty it will be renormalized to an empty bond; all other configurations are renormalized into a perimeter bond. Therefore all configurations in Fig. 1(a) will be renormalized to the vertical perimeter bonds, and all configurations in Fig. 1(b) will be renormalized to vertical bulk bonds.In order to find the local growth probabilities on each bond, we notice that the particles are released from the top and adhere to perimeter bonds along the shortest path, and, if there is more than one such path for a particular particle, then each path has an equal chance to be chosen. Let us take configuration 1 of Fig. 1(a) an an example. If we denote p, , and p, 2 as the growth probabilities on the perimeter bonds 1 and 2, respectively. Ac-