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Aim: To examine cardiac function, body temperature and locomotor behaviour in the awake adenosine A1 receptor knock out mouse of both sexes. Methods: Male and female A1R (+/+) and (−/−) mice, instrumented with telemetric devices, were recorded during basal conditions and after drug administration. Results: Female mice had higher heart rate, body temperature and locomotion, both during daytime and during the night. Awake A1R (−/−) mice had a slightly elevated heart rate, and this was more clear-cut in males. Heart rate was also higher in Langendorff-perfused denervated A1R (−/−) hearts. Body temperature was higher in A1R (−/−) males and females; locomotor activity was higher in A1R (−/−) females, but not in males. The adenosine receptor agonist R-PIA (0.2 mg kg−1) decreased heart rate and body temperature, but less in A1R (−/−) animals than in A1R (+/+) mice ( P < 0.001 in both parameters). The unselective adenosine receptor antagonist caffeine had a minor stimulatory effect on heart rate in lower doses, but depressed it at a dose of 75 mg kg−1. Body temperature was increased after a low dose (7.5 mg kg−1) of caffeine in both sexes and genotypes, and markedly reduced after a high dose (75 mg kg−1) of caffeine. An intermediary dose of caffeine 30 mg kg−1 increased or decreased body temperature depending on genotype and sex. Locomotor responses to caffeine were variable depending both on genotype and sex. Conclusion: Thus, the adenosine A1 receptor is involved in the regulation of heart rate, body temperature and locomotor activity, but the magnitude of the involvement is different in males and females. [ABSTRACT FROM AUTHOR]