Autonomic nervous dysfunction is a well-recognized symptom in chronic kidney disease (CKD). We have reported that slow breathing exercise (SBE) enhances parasympathetic nervous activity in healthy males. This study aimed to evaluate the effects of SBE in CKD patients. Six male outpatients with severe CKD participated. SBE (six abdominal breaths per minute for each 15-minute session) were performed twice a day for around four weeks. Before and after the SBE trials, electrocardiogram, blood pressure, respiratory rate, skin temperature and skin blood flow were obtained at rest. Autonomic nervous activity was evaluated with power spectral analysis of heart rate variability. High frequency (HF) and low frequency (LF) powers corresponded to the para- sympathetic nervous activity and sympathetic-parasympathetic nervous activity, respectively, and LF/HF ratio corresponded to sympatho-vagal balance. After SBE, respiratory rate and LF/HF ratio decreased, diastolic blood pressure tended to decrease, and HF and skin temperature tended to increase. Sympatho-vagal balance is shifted to sympathetic dominance in CKD patients compared to healthy adults. Our results showed that SBE can shift autonomic balance to parasympathetic nerve dominance even in severe CKD patients. SBE has the potential to improve autonomic nervous imbalance in CKD patients.