Summary Aim: The aim of this study is to present normal values for 99mtechnetium mercaptoacetyltriglycine renal uptake kinetics as a function of age, sex and circadian rhythm in mice using multi-pinhole SPECT. Methods: Dynamic multi-pinhole SPECT semistationary acquisitions consisting of 10 20 s frames followed by 25 50 s frames began prior to intravenous injection of 50 MBq in 12 female (F) and 12 male (M) C57BL/6N mice. Each mouse had follow-up imaging at 1, 3, 6, 12 and 22 months of age. To assess physiological changes related to circadian rhythm, animals were imaged during light (sleeping phase, SP) and dark conditions (awake phase, AP). Renal excretion time activity curves were analysed to determine maximum time to peak uptake (Tmax). Results: There was an age-related effect on renal Tmax. In one-month-old mice median Tmax (1.8 min) occurred later than in 3-month-old mice (1.7 min; p = 0.035). Thereafter, mice showed continuously increasing time to renal Tmax up to an age of 22 months (2.3 min; p < 0.001). Female mice showed a significantly later renal Tmax than males (F 2.1 min, M 1.7 min; p < 0.001) from 3 months onwards. An effect of circadian rhythm on renal uptake was also observed with borderline relevance. Pooled results for all animals showed that renal Tmax appeared at a later timepoint after injection during SP (2.0 min) than during AP (1.8 min; p = 0.019), while in age and sex matched animal groups no significant differences were observed. Conclusion: This study showed that kidney function in mice is dependent on age and sex, whereas circadian rhythm does not cause a significant effect. Therefore, age and sex should be considered as important study design considerations for renal scintigraphy in mice, while the impact of circadian rhythm seems negligible.