A previous report described selective electrical activity of the cerebral hemispheres with uninostril breathing. In the present study, middle latency auditory evoked potentials (MLAEPs) were recorded from symmetrical scalp sites during the practice of uninostril yoga breathing. There were two sessions (40 min each) of right nostril yoga breathing (RNB) and of breath awareness (BAW), with (i) 'before', (ii) test (either RNB or BAW) and (iii) 'after' periods. The participants were 14 male volunteers aged between 18 and 33 years, and the setting was a yoga centre. MLAEPs were recorded from symmetrical scalp sites (C4 and C3). During RNB, the peak amplitudes of two negative components (viz. Na wave and Nb wave) were significantly increased on the right side. Increased peak amplitudes of Na and Nb waves suggested that RNB increased the number of neurons recruited on the right side, suggesting a possible application of RNB in certain psychiatric disorders with cerebral hemispheric imbalance.