Jejuno-ileal bypass (JIB) was first decribed in the late 1960s and peaked in popularity in the mid 1970s. Although the operation produced satisfactory weight loss, it also leaded to various complications, including hepatic cirrhosis, malabsorption, diarrhea, hiperoxaluria and nephrolithiasis.While the effect of reversal on hepatic function has been well studied, there is little information regarding improvement in renal function. We present a 57 year old woman who underwent a jejuno-ileal bypass in 1968 for morbid obesity. The patient experienced excellent weightloss, but developed bilateral kidney stones that required multiple procedures. The primary indication for jejunoileal bypass reversal was intractable calcium oxalate stones and renal function impairment. Changes in urine creatinine, BUN, oxalate and citrate excretion, BMI and symptoms were recorded after the reversal procedure. After 3 months of follow up, the levels of oxalate excretion, urine creatinine and BUN normalized. Her symptoms improved significantly. No major changes were observed in citrate excretion and BMI. JIB reversal normalizes urinary oxalate excretion and renal function. Reversal improves urinary citrate excretion and kidney stone related symptoms.