Primary immunoglobulin A (IgA) nephropathy is characterized by microhematuria and proteinuria and by the deposition of IgA in the glomerular mesangium. Steroid was a main drug for treatment of IgA nephropathy. However, some of children with IgA nephropathy are resistance to steroid treatment, but the therapy for steroid-resistant IgA nephropathy was not established. There have been reports on the efficacy of tonsillectomy as an initial treatment for IgA nephropathy in adults and children. We examined whether tonsillectomy with methylprednisolone pulse therapy (tonsillectomy pulse therapy) was effective as rescue treatment for steroid-resistant pediatric IgA nephropathy. We studied 11 patients (age at onset and duration of follow-up, 11.7 +/- 2.0 and 6.2 +/- 1.1 years) who had been diagnosed with steroid-resistant IgA nephropathy. Clinical features, laboratory data, and pathological findings were retrospectively compared between before and after tonsillectomy pulse therapy. Urinary protein excretion was significantly decreased at 24.7 +/- 7.3 months after tonsillectomy pulse therapy. On renal pathologic examination of 6 patients who underwent renal biopsy at 17.1 +/- 6.9 months after tonsillectomy pulse therapy, the activity index, an index of inflammation, was lower compared to the index evaluated before the therapy, but the chronic index, an index of renal sclerosis, remained unchanged. At 24.7 +/- 7.3 months after tonsillectomy pulse therapy, seven patients had normal urine and four had minor urinary abnormalities; namely, none had active renal disease or renal insufficiency. Our findings suggest that tonsillectomy pulse therapy may be effective as rescue treatment for steroid-resistant IgA nephropathy in childhood.