Five patients receiving increased dose or frequency of pamidronate beyond the recommended dose (90 mg/monthly) exhibited nephrotic proteinuria (range 3.96-24 g/24 h). On dose reduction or discontinuation, three of these patients showed decreased proteinuria to normal levels (< 1 g/24 h), and proteinuria decreased to 4.5 g/24 h from a peak of 24 g/24 h in one patient. One patient on haemodialysis (hence not evaluable) had proteinuria of 2 g/24 h and elevated creatinine levels. One other patient continued to show elevated creatinine levels (272.8 micro mol/l). Renal biopsies obtained in two patients revealed focal segmental glomerulosclerosis.