BACKGROUND Mesangial deposition of IgA (MCA) is a very rare finding in minimal change disease and has previously been considered a pure coincidence. In the U.S. and Europe only anecdotal case reports exist. To date, there has been no consensus on nomenclature and categorization of this entity. We describe 2 cases of MCA with analogue histological findings but relevant differences in clinical presentation, and we discuss the clinical implications of mesangial IgA deposition in minimal change nephrotic syndrome. METHODS A 47-year-old female was admitted to hospital with nephrotic syndrome, microscopic hematuria, arterial hypertension and slight impairment of renal function 3 weeks after an unspecific upper airway infection. A 42-year-old male presented with nephrotic syndrome, microscopic hematuria, normotension and normal renal function. Both of the nephrotic syndromes were steroid-responsive and steroid-dependent. RESULTS The clinical presentation of the male patient was consistent with the features of minimal change glomerulopathy, whereas the female patient combined signs of minimal change disease and IgA nephropathy. Light microscopy revealed mesangial IgA immune deposits and slight mesangial hypercellularity. Electron microscopic studies of MCA patients disclose diffuse effacement of glomerular foot processes. CONCLUSIONS Our cases and a review of the literature indicate that the histological diagnosis of MCA may comprise different pathogenetic entities. From the clinical point of view, MCA has to be regarded as a minimal change nephrotic syndrome with symptomatic or asymptomatic mesangial IgA deposition. IgA deposition constitutes a risk factor for impairment of renal function and indicates a frequently relapsing course.