As part of a broader effort to establish processing-structure-property relationships in PLLA/nHA, which is currently under consideration for bioresorbable scaffolds for bone repair, hot stage optical microscopy and differential scanning calorimetry have been used to investigate the solidification behavior of a series of medical grade PLLA/nHA nanocomposites. The presence of the nHA resulted in an increase in the number of spherulites per unit volume during isothermal crystallization, but there was a substantial decrease in the spherulite growth rate with increasing nHA content in the temperature range 100-130 °C, argued to be associated with a significant increase in the melt viscosity in the presence of the nHA. The consequences for the global solidification rates and the phase structure of the PLLA/nHA nanocomposites are discussed.