Experimental Pathology Laboratories, PO Box 12766, Research Triangle Park, NC 27709, USA. brix@niehs.nih.gov Abstract The NTP has a long history of using Fischer rats and has compiled a large database of incidences of lesions seen in control animals. Such a database is lacking for Harlan Sprague-Dawley (SD) rats. The intention of this paper is to report spontaneous lesions observed in female vehicle control Harlan SD rats, and to compare the incidence in 2 strains of rats (Fi