This morphological pattern may also accompany other more obviousor serious changes and it may be a point in progression or regression ofglomerulonephritis in a patient who at an earlier or later time has a differentpattern of glomerular injury. The clinical presentation as well as themicroscopic findings (morphological and immunohistological) are veryimportant as they are prognostic indicators.This histological study was conducted to study the characteristics ofdiffuse mesangial proliferation and the associated histopathological findingsin the interstitium, tubules and blood vessels. To correlate the findings withavailable clinical data and immunohistochemical results.This work showed high frequency of minimal and mild mesangialproliferation grades. Also, the frequency of mesangial matrix expansion washigh. Mild matrix expansion was the most common grade. Irregular matrixexpansion was found only in (5%) of the studied cases. It was found thatthere was significant statistical correlation between grades of mesangialproliferation and mesangial matrix expansion.The clinical data of our patients revealed that proteinuria was the mostfrequent clinical presentation (80%), of which nephritic range represented(57.5%). Hematuria was the second common presentation (21%), of whichgross hematuria was found in (61.90%). Mesangial proliferation wasprobably secondary to systemic diseases in (7%) of the studied eases.