In vivo and in vitro treatment of mammary glands with xanthosine has been shown to increase mammary stem/progenitor cell population in heifers. Inosine, a ribonucleoside that is related to xanthosine, has been reported to increase milk production in transgenic goats. However, the underlying mechanisms of these effects are poorly understood. The goal of this study was to examine the effects of xanthosine on the mammary stem cell population and milk production in dairy goats. Primiparous Beetle goats (n = 7) were assigned to the study. Five d after kidding, one gland (either left or right) was infused xanthosine (TRT) twice daily (2×) for 3 d and the other gland served as control (CON). Mammary biopsies were collected at 10 d and RNA was isolated. Daily milk yield per gland was recorded 10.5 +1.3 d after biopsies for 7 wk. Average milk yield in TRT glands was increased 2% (P = 0.04, paired t-test) relative to CON glands until 7 wk. After 7 wk, milk yield of TRT and CON glands did not differ. Analysis of milk composition revealed that protein, lactose, fat and solids-not-fat percentages remained the same in TRT and CON glands. Expression of transcripts for β-lactoglobulin (BLG4), β-casein (CSN2), estrogen receptor-α (ESR1) and aldehyde dehydrogenase 1 (ALDH1, a mammary stem cell marker) was significantly increased and α-lactalbumin (LALBA) and casein α-S2 (CSN1S2) tended to be increased in TRT glands. These results support the hypothesis that xanthosine increases milk production and the mammary stem cell population.