The amounts(such as volume,surface area,length and number)of histological structures can be estimated with ste-reological(morphometric)methods by measuring tissue sections,but the section tissue has usually undergone processing such as fixa-tion,dehydration,embedding,sectioning and staining and the measured results reflect the quantitative characteristics of structures after the processing.The volume and others of structures will likely change after tissue processing,thus affecting the results of stereological estimation;to correct the results so as to reflect the quantitative properties of the structures before processing,the respective volumes of the organ tissue before and after processing need to be obtained to estimate the overall tissue volume change post-processing and the cor-responding change of structures of interest in the tissue.The present paper deals,in a systematic and comprehensive way,with the theo-retical basis for correction of stereological estimates using the organ volumes before and after processing,how to obtain the volumes,how to use them to correct different stereological results,in which cases separate experiments are needed for correction,and how to imple-ment the experiments for correction.An important and novel part of the present paper is introduction of a new concept:the organ volume after tissue processing should be categorized into two volumes-actual and virtual volumes;corrections for stereological estimates based on measurements in the three-dimensional space(within the actual section tissue)and those on two-dimensional planes(on sectional planes)should be based on the actual and virtual volumes,respectively.