Endocrine-disrupting chemicals (EDCs) interfere with hormonal signalling pathways and pose significant risks to reproductive health. Phenylmercuric acetate (PMA), an organomercury compound formerly used as a preservative and antimicrobial agent, has raised concerns due to its persistence, bioaccumulative nature, and potential endocrine-modulating properties. The present study evaluated the estrogenic activity of PMA using the uterotrophic bioassay in ovariectomized female Wistar rats. Animals were allocated into four groups (n = 6 per group): vehicle control (corn oil), positive control administered 17α-ethinyl estradiol (10 µg/kg, subcutaneous), and two PMA-treated groups receiving 2 mg/kg/day and 8 mg/kg/day orally for three consecutive days. Uterine wet weight, blotted weight, and uterine fluid content were assessed as primary endpoints, supported by histopathological examination of uterine tissue. PMA administration resulted in a dose-dependent and statistically significant increase in uterine weights and fluid content compared with controls, with the high-dose group exhibiting pronounced uterotrophic responses. Histological analyses revealed epithelial proliferation, stromal remodelling, inflammatory infiltration, and glandular degeneration, with severity increasing at higher PMA doses. No mortality or overt clinical toxicity was observed, although reduced food intake and mild body-weight changes were noted at the highest dose. These findings demonstrate that phenylmercuric acetate exerts estrogen-like effects in vivo and induces significant uterine structural alterations. The study highlights PMA as a potential endocrine disruptor with reproductive toxicity implications, underscoring the need for stringent regulatory evaluation and further investigation into its long-term health effects