Objectives : The aim of this clinical experiment was to investigate the effect of KamiWooseul-tang on low back pain and kidney function. Methods: We investigated 64 low back pain patients. We treated the patients with acupuncture, bed rest, herbal medicine, physical therapy. The patients were divided into two groups as follows, 32 patients (with normal renal function) were treated with only KamiWooseul-tang. Another 32 patients were treated with a commonly used herbal medicine. Results : The obtained results are summarized as follows. The patients were 43.8% male and 56.2% female. Their age were 20s 15.6%, 30s 25%, 40s 17.2%, 50s 9.3%, 60s 18.8% 70s 12.5% and 80s1.6%. Duration is most common in the most acute stage (< 1 week), next was chronic stage ( >6 months ), acute stage (1 week ~ 1 month) and subacute stage(l months ~ 6 months) in turn. Cure rate increased step by step after herb-medicine administration. Duration of patients had no relation with cure rate(P>0.05). The KamiWooseul-tang was more effective than the commonly used herbal medicine after 3 weeks therapy (P<0.05). Serum BUN and Creatinine level in KamiWooseul-tang group changed from $14.69{pm}4.0,{;}0.76{pm}0.19(mg/dl)$ before adminstration to $13.64{pm}3.92{;}0.77{pm}0.19,{;}13.48{pm}3.00{;}0.82{pm}0.21,{;}13.26{pm}3.73{;}0.87{pm}0.21(mg/dl)$ at 7th, 14th, and 21st days of administration respectively. Urinalysis showed no specific change in the KamiWooseul-tang group. During medication serum-electrolyte was within normal range. Conclusion : Therefore KamiWooseul-tang was more effective than the commonly used herbal medicine and there was no clinically remarkable difference in the serum BUN, Creatinine level, urinalysis and serum electrolyte between pre-medication and post-medication in the KamiWooseul-tang group.