Objective To investigate the different expression patterns of the phenotypic marker protein for stromal cell, proliferating cell nuclear antigen(PCNA) and estrogen receptor α(ERα) in normal human prostate (NP) and benign prostatic hyperplasia (BPH) tissue, and to locate cells stained positively with the marker protein for stromal cell and PCNA or ERα at the same position. Methods Serial sections of 4 NP and 8 BPH specimens were subjected to immunohistochemistry (IHC) staining for vimentin, α-smooth muscle actin (α-SMA), myosin, PCNA and ERα. Results Compared with that in the NP tissues, the number of α-SMA positive cells increased significantly in BPH tissue, and the number of vimentin positive cells increased moderately in the stroma and prominently surrounding the acinus and in the basal layer. In BPH tissue, the myosin and ERα staining signal was lost in the stromal cells surrounding the acinus, and the positive staining cells gathered into bunches in the stroma far away from the acinus, while the positive cells were sporadically distributed in the NP tissue. The PCNA positive cells increased moderately in the stroma and increased significantly in the basal layer. The serial sections staining results showed that there was a colocation of PCNA, vimentin and ERα in basal cells, and a colocation of myosin and ERα in stromal cells. Conclusion There are apparent phenotypic modulations of the stromal cells in the BPH specimen co