A 42-year-old female presented with progressive proximal muscle weakness, generalized hyperreflexia, marked bone pain, severe lumbago and knee arthralgia. Electromyographic study showed short-duration (5-10 msec), variable amplitude (200-2500 microV) polyphasic potentials. A muscle biopsy specimen revealed non-specific type II fiber atrophy. After a comprehensive laboratory work-up, adult Fanconi syndrome was diagnosed. The patient's symptoms, including bone pain and proximal muscle weakness, were relieved after a six-week supplement of tricalcium phosphate, vitamin D3 and sodium bicarbonate. The hyperreflexia also became less brisk.