Nicotinic acetylcholine receptors are assembled from a pool of 9 and 3 subunits into functional pentamers in peripheral autonomic neurons. The contribution of different subunits to native, physiologically important nAChR for synaptic transmission in autonomic ganglia is unclear. Here we examined the importance of the 7 subunit for parasympathetic innervation of the heart. Methods. Normal (C57BL/6J), 7 deficient (Chrna7), and wildtype littermate mice were implanted with telemetry devices and under conscious, unsedated conditions, ECG recordings were obtained at baseline and following atropine, propranolol, and hexamethonium bromide administration. Spectral analysis of heart rate variability (PSA) was performed for evaluation of resting autonomic tone to the heart. At the completion of conscious studies, animals were anesthetized and underwent electrical stimulation of the vagus nerve (VS) while recording R-R intervals. Results. Heart rate at baseline, after atropine, propranolol or hexamethonium was similar in all three groups of animals. PSA curves were similar between normal, wildtype and Chrna7 mice. VS showed no difference between control and Chrna7 mice throughout the range of stimulation (5-20 Hz). Discussion. Mice deficient in the 7 nAChR subunit do not display differences in resting autonomic tone to the heart at baseline or under conditions of single and combined autonomic blockade. Electrical stimulation of the vagus nerve showed no difference in heart rate responses between normal and 7 deficient mice. These data support previous findings in vitro and highlight the important differences in function between nicotinic receptor subtypes since 3 deficient mice display major autonomic dysfunction. We conclude, that the 7 subunit does not contribute critically to resting parasympathetic control of the heart.