The effect of wearing different types of textiles on sexual activity was studied in 75 rats which were divided into five equal groups: four test groups and one control. Each of the four test groups were dressed in one type of textile pants made of either 100% polyester, 50/50% polyester/cotton mix, 100% cotton or 100% wool. Sexual behaviour was assessed before and after 6 and 12 months of wearing the pants and 6 months after their removal. The rate of intromission to mounting (I/M) was determined. The electrostatic potentials generated on penis and scrotum were also measured by electrostatic kilovoltameter. At 6 and 12 months of wearing the polyester and polyester-cotton mix pants, the I/M ratio was significantly reduced compared to the pre-test levels and the controls (p < 0.0001). The reduction was more manifest in the polyester than in the polyester-cotton mix group, and at the 12th month than at the 6th month of examination. The I/M ratio of the cotton and wool groups showed insignificant changes (p > 0.05) at the 6th month of the study and a significant increase at the 12th month (p < 0.01). Six months after removal of the pants, the I/M ratio returned to the pre-test levels (p > 0.05) in the four groups. The polyester-containing pants generated electrostatic potentials while the other textiles did not. These potentials seem to induce 'electrostatic fields' in the intrapenile structures, which could explain the decrease in the rats' sexual activity.