The roles of vitamins and minerals in reproductive tract development and attainment of puberty have received very little attention. We examined the effects of vitamin and mineral supplementation on weight and follicular development of ovaries, ovarian concentration of luteinizing hormone (LH) receptors and weight and length of uteri in prepuberal gilts. Thirty crossbred (Large White x Polish Landrace) 160- (Group I; 75-85 kg) and thirty 180-dayold (Group II; 85-95 kg), randomly assigned gilts received 3100 kcal ME/kg/day (control; n=15) or supplemented (n=15) with 25 g of minerals (MMT-Polfa, Kutno, Poland) for 14 days and were slaughtered immediately thereafter. Additionally, both mineral-supplemented subgroups received a single i.m. injection of vitamins (A, D₃, E, B₁, B₂, B₆, B₁₂ , C and PP). The supplementation treatment did not affect the length of uterine horns or weight of ovaries in either group I or group II. The LH receptor concentration in the ovary (fM/mg protein) was twice as high (P<0.05) in the supplemented than in control gilts in both group I (1.21±0.25 vs 2.52±0.51) and II (1.87±0.23 vs 3.77±0.63). The total number of follicles was 20% higher in the ovaries of younger gilts (Group I). In the ovaries of younger gilts supplemented with vitamins and minerals, the number of class 1-3 mm diameter, healthy follicles was significantly higher (P<0.05). The total number of atretic follicles was 27.5% lower in this subgroup. No significant changes in number or distribution of healthy and atretic follicles were found among the supplemented- and control animals of the older group (Group II). The results of this study show that supplementation with vitamins and minerals can influence follicular development and stimulate ovarian LH receptor induction in prepuberal gilts.