The aim of this study was to investigate the potential effects of vitamin K1 supplementation on skeletal changes related to fluoride in growing rats. Forty male Wistar rats aged 4 weeks were assigned at random into three groups: high-dose fluoride (125 ppm) group; high-dose fluoride + vitamin K1 (0.2 mg/(g day)) group; and a control group. The experimental period was 12 weeks. The L3 vertebrae and the right tibiae were removed, and specimens were analysed by histologic and histomorphometric methods. Quantitative radiodensitometry was also employed to assess the differences in bone mineral density (BMD) between the groups. In the tibia, total tissue area was higher in the study groups than the control group (P < 0.05). Cortical bone area was slightly higher in the fluoride + K1 group than the fluoride group, and marrow cavity area was lower in the fluoride + K1 group (P < 0.05). In the L3 vertebral cancellous bone, bone volume, trabecular number and trabecular thickness were higher in the study groups than the control group (P < 0.05). Trabecular separation was reduced in the study groups (P < 0.05), and was lower in the fluoride + K1 group than the fluoride group (P < 0.05). The fluoride + K1 group had a significantly higher BMD than the other groups (P < 0.05), and the fluoride group had a significantly higher BMD than the control group (P < 0.05). The present study found that fluoride administration increased bone mass in both vertebrae and tibiae in growing rats. Simultaneous administration of vitamin K1 and fluoride resulted in an additional increase in vertebral bone mass.