Mesangial IgA glomerulonephritis (MIgAGn) is the most common biopsied primary glomerulonephritis worldwide, with a poor long-term prognosis for renal function in over a third of all patients. No proven therapy currently exists for MIgAGn. Recent studies have suggested some benefit with mycophenolate mofetil (MMF), especially in hypertensive patients with kidney failure and proteinuria, though other studies have failed to corroborate these findings. We report eight adult patients with biopsy proven MIgAGn followed in a single hospital. They all received angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers. Compassionate use of MMF was based on the presence of clinical and analytical data suggesting a high risk of short- to medium-term progression to chronic renal failure. MMF treatment was stopped after two and three months in two patients who had advanced renal failure at the start of therapy because of disease progression and greater fluid retention. Several months later they both required dialysis and kidney transplantation. The mean duration of MMF therapy in the other six patients was 15 (range: 10-18) months. The mean serum creatinine concentration fell from 1.82 +/- 0.47 to 1.55 +/- 0.41 mg/dl (p = 0.04). Protein loss in 24-hour urine collection fell from 1.95 +/- 1.35 to 0.77 +/- 0.58 g/day (p = 0.02). These results in this low number of patients showed that treatment with MMF in high-riks patients with MIgAGn and early stage kidney failure generally stabilized the disease and reduced proteinuria. MMF was well tolerated and may be of some benefit in a subgroup of patients with MIgAGn and a poor prognosis.