This study was conducted to investigate the effects of caffeine on lipid and mineral content in the serum of rats given a caffeine free diet(FC), a low caffeine diet(LC), a medium caffeine diet(MC), a high caffeine diet(HC) or a super-high caffeine diet(SHC) for 5 weeks. Thirty male Sprague-Dawley rats(body weight, $110{pm}0.3$ g) were blocked into 5 groups and fed diets with or without pure caffeine. Caffeine intake models showed a lower mean-weight gain, food intake and food efficiency in the high caffeine diet groups(MC, HC and SHC groups) than the groups receiving a caffeine free or low caffeine diet(FC and LC groups). Serum total lipid, total cholesterol and LDL-cholesterol levels decreased, but the serum HDL-cholesterol level increased according to the increase in caffeine intake. Serum total lipid, HDL-cholesterol and serum triglyceride were significantly lower in the HC and SHC groups than the FC group. All of the serum minerals decreased as caffeine intake increased. Serum iron, calcium, magnesium and phosphorus significantly decreased in the HC and SHC groups compared to the FC group. Caffeine intake was associated with less weight gain and reduced serum total cholesterol, triglyceride and total lipid. The results suggest that rats fed high amounts of caffeine may be susceptible to osteoporosis due to their low levels of calcium, magnesium and phosphorus.