Armadillos (Cingulata: Dasypodidae and Chlamyphoridae) are the only mammals bearing an osseous carapace. Most mammals have rapid growth rates and require high mineral levels. However, armadillos feed mainly on insects, a poor source of calcium and phosphate. This raises the question how lactating females obtain the needed minerals to provide their offspring sufficient quantities for the development and hardening of their carapace. The objective of this study was to evaluate whether there are differences in the mineral density of the carapace and endoskeleton of reproductive (especially lactating) and non-reproductive female armadillos, and those of males. We performed computed tomography of 32 female and 13 male dead pichis (Zaedyus pichiy) of different age classes and reproductive status and compared bone mineral density (BMD) of their marginal scutes, compact and spongy bone of the carapace, and femoral bone. Juveniles of both sexes had significantly lower BMD than adults. Average BMD values of the marginal scutes, compact and spongy bone of the carapace, femoral head, spongy bone, and femoral cortical bone of lactating females were similar to those of adult males and significantly higher than values of adult females without signs of gestation or lactation. We conclude that lactating females do not seem to lose bone density, at least from the carapace and femur, during lactation. However, our results suggest that a high BMD may be necessary to support reproduction in female pichis.