<p>This study aimed to assess the effects of feeding slow-release boluses of antioxidant and/or calcium on calcium homeostasis, productive and reproductive performance in high-producing dairy cows during the summer season. At the beginning of the close-up period, two hundred multiparous dairy cows were divided into two groups of with (+ A) or without (-A) antioxidant slow-release bolus administration. Then, each of the two initial groups was further divided into two subgroups of with (+ C) or without (-C) calcium slow-release bolus. Therefore, the experimental groups were + A + C, +A-C, -A + C, and -A-C during postpartum period (50 cows per group). The results indicated that + A reduced serum non-esterified fatty acids (NEFA) and NEFA: Albumin ratio during prepartum period (<i>P</i> = 0.03). Moreover, the + A cows had higher serum beta-hydroxy butyrate (BHBA), lower cholesterol, and alanine transferase during the postpartum period (<i>P</i> &lt; 0.05). On the other hand, the + C cows had lower serum BHBA, and aspartate aminotransferase throughout the postpartum period (<i>P</i> &lt; 0.05). The cows in group + C had higher milk yield, fat and energy corrected milk, milk fat, and protein content but lower somatic cell count than -C cows postpartum (<i>P</i> &lt; 0.05). The treatments of + C and + A had shorter days to the onset of ovarian activity and uterine involution compared with -C and -A cows (<i>P</i> &lt; 0.05). In conclusion, administration of slow-release calcium boluses improve production performance while its combination with antioxidant bolus seems to be a promising strategy for improving the metabolic and reproductive status of dairy cows during heat stress.</p>