Objective: Renal fibrogenesis is a process common to all progressive kidney diseases. The main executive cell of this process is the fibroblast, by secreting and remodeling the extracellular matrix. The number of fibroblasts is minor in healthy kidney interstitium, but it increases during the process of fibrosis. Their morphology and immunophenotype vary due to different intrinsic and extrinsic factors, thus making their identification and visualization, as well as determination of their origin, very difficult. Method: We performed morphological and immunohistochemical analyses on kidney biopsies with primary glomerulopathy and interstitial fibrosis, using the following antibodies: Vimentin, α-SMA, S100A4, Cadherin 9 and CD34. Results: Interstitial fibrosis with focal, rather than diffuse distribution, was present in all analyzed cases. The total interstitial fibroblast population was positive for Vimentin, majority of the cells were positive for S100A4, and a smaller proportion of cells were positive for α-SMA, Cadherin 9 and CD34. Furthermore, different cells in the fibroblastic population showed positivity for different markers. Conclusion: The above stated observations contribute to the theory that different subpopulations of fibroblasts, with different origin, take part in the renal fibrogenesis.