Strains and stocks of rats most widely used in biomedical research are listed in the table below. This is based on a PubMed  search of the number of papers using the designated strain or stock for the years 2001-2005. Note that inbred strains were used on only 11.9% of occasions, with the vast majority of work being done using outbred  Sprague-Dawley or Wistar rats. Only 12 inbred rat strains have a PubMed MeSH  heading.

The most popular rat inbred strains are listed in  descending order of the number of citations. Thus, the most widely  used strain was F344, accounting for 32.1% of occasions on which an inbred  strain was used, next being LEW at 22.5% and so on.

A list of inbred strains and their characteristics is  maintained on the Jackson Laboratory web site.

There has been significant under-investment in inbred rat strains over a period of many years. A lot is known about F344, but relatively little about all the other  strains. The Rat Phenome project being run by a Japanese consortium is characterising many isogenic rat strains for a wide range of physiological, biochemical and morphological  parameters.

Stock/strain	Number of papers	MESH	% All rats
Sprague-Dawley*	49,477	Yes	40.9	-
Wistar*	41,929	Yes	34.7	-
Long-Evans*	13,467	Yes	11.1	-
Mutants	1,601	Yes	1.3	-
Inbred strains	14,353		11.9
Total * Outbred stocks	120,827	-	100.0	-
Inbred strains only	-	-	-	-% Inbred rats
F344	4,611	Yes	3.8	32.1
LEW	3,227	Yes	2.7	22.5
SHR	2,086	Yes	1.7	14.5
WKY	1,821	Yes	1.5	12.7
BN	989	Yes	0.8	6.9
Dahl SS and SR	318	Yes	0.3	2.2
WF	309	Yes	0.3	2.2
ACI	224	Yes	0.2	1.6
BB	209	Yes	0.2	1.5
OLETF	171	Yes	0.1	1.2
WAG	95	No	0.1	0.7
BUF	90	Yes	0.1	0.6
PVG	79	No	0.1	0.6
LEC	66	Yes	0.1	0.5
OM	16	No	0.0	0.1
COP	15	No	0.0	0.1
BDIX	12	No	0.0	0.1
BDII	8	No	0.0	0.1
BH	7	No	0.0	0.0
Total inbred strains	14,353	-	11.9	100.0