Two-stage melting of the dilute gels of poly(gamma-benzyl L-glutamate) in benzene has been studied by differential scanning calorimetry, Ride-angle X-ray diffraction, and small-angle X-ray scattering using synchrotron radiation. Differential scanning calorimetry measurements show that the traces on heating exhibit two endothermic peaks at about 25 degrees C and at about 31 degrees C, thereby indicating the melting of two types of aggregates, while those on cooling exhibit no exotherm even at 0 degrees C, thereby indicating a large thermal hysteresis. Wide-angle X-ray diffraction measurements show that the profiles yield little of interest other than diffuse halos from the solvent except a diffuse small-angle scattering, thereby indicating that the aggregates do not contain a solid crystalline phase but a crystal-solvate phase. Small-angle X-ray scattering measurements show that the two-stage melting of the aggregates can be attributed to a melting first of the bundles of three rods and then of the bundles of two rods and that, above the two-stage melting temperature, the gels transform into the dilute and isotropic solutions, in which the poly(gamma-benzyl L-glutamate) stiff chains are randomly dispersed and do not interact with each other. We suggest that the intermolecular interactions causing the bundles to aggregate are induced by the solvent.