Propiconazole is a systemic fungicide from the triazole group used to control a wide range of diseases. This poison causes cellular, genetic and metabolic damage in animals. A bone is a hard tissue whose content is constantly changing. Longitudinal growth of the bone occurs through the growth plate, which is a cartilaginous structure at the end of the body's long bones. During puberty, while the growth plate closes (ossifies), the longitudinal growth of the bone stops. This study aimed to investigate propiconazole's effect on growth plate width changes (including the area of proliferating cells and the area of hypertrophied cells) in immature rats. This experimental study was conducted on 12 immature male Wistar rats randomly divided into control and propiconazole groups. The treatments were done by oral gavage for 28 days. On the 28th day, the dead animals and the left leg femur were separated for histomorphometric studies of the growth plate width of the femoral epiphysis. Investigations were carried out by (Rasband Wayne, 40g.1. ver, ImageJ, USA, NIH), and the significance of the results was done by ANOVA analysis of variance and Tukey's test. The width of the growth plate in the propiconazole group had a significant decrease compared to the control group (P = 0.0126), which is a decrease in the width of the proliferating area (P < 0.001) and an increase in the width of the hypertrophied area (P = 0.016). Propiconazole leads to a decrease in the width of the growth plate of the femoral epiphysis of immature rats. It can be a factor in disrupting the process of longitudinal bone growth and premature closure of the growth plate.