Calfhood diarrhea is the most common cause of mortality in dairy calves. Septicemia is an important sequela of diarrhea, and the primary justification for antimicrobial treatment for diarrhea. Farm workers make routine decisions to initiate antimicrobial therapy based on clinical signs, yet there is a lack of criteria associated with bacteremia. The prevalence of bacteremia in diarrheic calves has been estimated to be 30%; however, this estimate included calves presented to a veterinary hospital or raised for veal, and may not reflect the prevalence in calves on commercial dairy operations. Thus, the objective of this study was to determine the prevalence of bacteremia in diarrheic dairy calves and identify clinical signs associated with bacteremia. We hypothesized that the prevalence of bacteremia would be less than 30% in calves with diarrhea, and that clinical signs, such as temperature and respiratory rate, would be accurate predictors of bacteremia. Calves (≤21 d of age) were enrolled across 2 dairy farms into a diarrheic or clinically healthy group (control to assess aseptic technique). Diarrheic calves enrolled presented with loose to watery stool, dehydration (assessed by skin tent) or depression (assessed by suckle reflex and ability to stand), and were not previously treated with antibiotics. Health assessments were performed at enrollment, and included respiratory signs, joint inflammation, navel score, temperature, and heart and respiratory rate. Following the health assessment, one aseptic blood sample was collected from each calf and cultured to determine bacterial species present using mass spectrometry. Associations between bacteremia and dichotomized health outcomes were analyzed using Fisher’s exact tests and continuous outcomes were compared using Student’s t-tests. The prevalence of bacteremia in diarrheic calves was 15.3% (17/111) and 18.5% (5/27) in clinically healthy calves. There was no association between clinical signs and bacteremia. The prevalence of bacteremia in the diarrheic group was significantly lower than previous estimates, indicating there may be opportunity to reduce antimicrobial use in calves with diarrhea that are not septicemic.