Two-step microwave sintering was applied in this study to process dense nano-structured bioceramics coupled with improved mechanical properties. The decrease in the average grain size to the nanolevel resulting from decreasing the sintering temperature to 850°C during two-step microwave sintering, led to an increase in the fracture toughness compared to conventionally two-step sintered bioceramic. The two-step microwave sintering could be a promising technique for the processing of nano-structured HAP bioceramics.