We studied the effect of some mineral waters and some of their constituents on the apical uptake of 14C-butyrate (14C-BT) and 3H-O-methyl-D-glucose (3H-OMG) by Caco-2 cells. Uptake of 14C-BT increased after a 20-minute exposure to 1 % (v/v) distilled water, and, compared to distilled water, it was decreased by Pedras Salgadas® 1 % (v/v) and Melgaço® 5 % (v/v), and increased by Vidago® 5 % (v/v). Moreover, it increased after a 48-hour exposure to Vidago® or Melgaço® waters (5 % (v/v)). Also, uptake of 14C-BT was reduced after a 20-minute exposure to MgCl2, MgSO4, or CaCl2. Uptake of 3H-OMG was reduced after a 20-minute exposure to Melgaço® water [1 % (v/v)], when compared to distilled water. Also, a 48-hour exposure to Pedras Salgadas® or Melgaço® water (5 % (v/v)) increased and decreased uptake, respectively. Finally, uptake of 3H-OMG decreased after a 20-minute exposure to MgSO4 or NaF. In conclusion, uptake of 14C-BT and 3H-OMG by Caco-2 cells is differently modulated by distinct mineral waters.