Investigation of 18 inbred and 6 F1 hybrid mouse strains has shown that the glomerular filtration rate, bodyweight and kidney weight showed strain- and sex-dependent differences. Covariance analysis showed stronger correlations (genetic and environmental) between glomerular filtration rate and bodyweight than between glomerular filtration rate and kidney weight. This was predominantly due to a high within-strain variation of kidney weight (56%) in male mice. Therefore an allometric regression was calculated between the 48 strain means of glomerular filtration rate (GFR) and bodyweight (BW): GFR = 0.036 x BW0.74. Thus the term BW0.74, a suitable correction term for comparing the heat production of different species, is also suitable for the correction of glomerular filtration rate within one species.