This study determined the effect of long-term administration of 4(G)-beta-D-galactosylsucrose (lactosucrose; LS) on intestinal calcium absorption. In a randomized, single-blind, parallel-group study, LS (n=9, 6.0 g twice daily) or a placebo (maltose; n=8, 6.0 g twice daily) was administered to healthy young women for 92 wk: the study also included a 4-wk post-administration period. All participants completed the study. Dietary nutrient intake; fecal weight, pH, and moisture content; fecal concentrations of short-chain fatty acids (SCFA), putrefactive products, ammonia, and minerals (calcium, magnesium, phosphorus, and iron); and serum calcium and osteocalcin concentrations were measured every 24 wk. Urinary pyridinoline (PYR) and deoxypyridinoline (DPD), and urinary calcium excretion were measured every 12 wk. Significant effects of oligosaccharide treatment, time, and the interaction between oligosaccharide treatment and time were observed for fecal pH, SCFA, ammonia, and putrefactive product values (p<0.05). Fecal pH, ammonia, and putrefactive product values decreased in the LS group, and the fecal SCFA concentration significantly increased during the administration period; these changes were not observed 4 wk post-administration. To examine the mineral balance of calcium, magnesium, and phosphorus in detail, all the participants completed a 6-d mineral balance study, sometime between week 56 and 60 of the longer study. During the mineral balance study, the daily calcium intake was set at 400 mg; all feces and urine were collected each day for 6 d after an 8-d acclimation period. In the balance study, fecal calcium excretion was significantly lower in the LS group than in the placebo group (p<0.05), and apparent calcium absorption and retention, apparent magnesium and phosphorus absorption, and magnesium retention were significantly higher in the LS group than in the placebo group (p<0.05). Our results suggest that the administration of LS produces a long-term enhancement of intestinal calcium absorption in healthy young women with lower than recommended calcium intakes.