The responses of right nostril breathing (RNB) and left nostril breathing (LNB) on cardio-respiratory and autonomic functions were investigated in healthy student volunteers of both sexes. The RNB and LNB groups comprised of 10 males and 10 females in each in age range of 17-22 years. Initially, in both groups control values of respiratory rate (RR), heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBF), peak expiratory flow rate (PEFR) and galvanic skin resistance (GSR) were recorded. The same parameters were recorded after 15 min (acute exposure) and 8 wks of training in RNB and LNB. In males RR (P<0.0001), SBP (P<0.05) and DBF (P<.05) fell significantly after 15 min of RNB. After 8 wks training in RNB, HR (P<0.01) decreased, SBP (P<0.001) declined more profoundly and RR (P<0.0001) and DBP (P<0.05) decrement was maintained. After 15 min of LNB, RR (P<0.01), HR (P<0.01), SBP (P<0.001) and DBP (P<0.01) declined significantly, on 8 wks training, RR (P<0.0001) and HR (P<0.001) decreased further, the decrement in SBP (P<0.001) and DBP (P<0.01) was the same. In females, RR alone fell significantly (P<0.05) after 15 min RNB. After 8 wks RR decrement was more profound (P<0.0001) and DBP also declined significantly (P<0.01). Similarly, 15 min LNB resulted in significant reduction in RR (P<0.001) and HR (P<0.05) only. Following 8 wks, of training in LNB, in addition to RR (P<0.0001) and HR (P<0.05) decrement, SBP (P<0.01) and DBP (P<0.05) also fell significantly. Both in males and females, GSR did not change significantly (P>0.05) either after RNB or LNB (15 min/8 wks). PEFR rose significantly (P<0.05) only in females after 8 wks of LNB. The results suggest that there are no sharp distinctions between effects of RNB and LNB either acute exposure (15 min) or after training (8 wks). However, there is a general parasympathetic dominance evoked by both these breathing patterns.