The anatomic pathology unit of the Massachusetts General Hospital (MGH) serves both the MGH (an 862-bed general hospital generating about 39,000 surgical accessions and 33,500 gynecologic and 8,500 nongynecologic cytology accessions annually) and the Massachusetts Eye and Ear Infirmary (MEEI, a 52-bed specialty hospital generating about 6,500 surgical accessions and 1,000 nongynecologic cytology accessions annually); the unit has 25 full-time equivalent (FTE) staff pathologists and pathology fellows providing its diagnostic services. On July 1, 1995, diagnostic specimen signout in this unit was changed to a system of complete subspecialization. The historical context and rationale for this change and the process of its implementation are presented, with a preliminary evaluation of its effects, including the impact on pathology staff, fellows, and residents. In addition, a mechanism for evaluation of equity and efficiency of pathologist work is presented, together with some discussion of the limitations of its accuracy. The authors conclude that to date the change has achieved many of its expected effects and that the process has worked smoothly. Further experience will clarify the overall results of the change.