The influence of calcination of the mixture of alumina powder and aqueous magnesium solution on the microstructure and properties of sintered bodies was investigated. The dry pressing technique was applied to form green bodies using granules prepared by spray drying both calcined and uncalcined alumina powders. Density, fracture strength and Weibull modulus were measured, and the microstructure was evaluated for sintered specimens prepared from calcined and uncalcined powders. Direct observation of the internal structure of sintered bodies was also applied to obtain information on the variation of defect distribution in sintered bodies. The effects of calcination on the properties and microstructure of sintered bodies are discussed, and it is concluded that the uniform mixing of alumina and magnesium source was responsible for the excellent properties of alumina ceramics made from the calcined powder.