Various nutritious nutritional-supplement gels are being marketed for use in veterinary medicine. This study was designed to determine whether serum calcium, phosphorous, or magnesium concentrations were different between cows given a gel containing calcium chloride as its active ingredient (treated) and cows given inert carrier gel (control). The study revealed a significant (P < 0.01) increase in serum total calcium concentration within 5 minutes of administration of a calcium gel given to cows within 1 hour of parturition. Serum total calcium concentration had returned to baseline value by 24 hours after calcium gel administration. Serum inorganic phosphorus concentration also increased significantly (P < 0.05) after treatment. Significant changes in serum magnesium concentrations were not detected.