Research regarding the accuracy of estimating blood loss by anesthesia providers has been limited, generally consisting of small sample sizes with conflicting findings. We conducted a prospective study using a convenience sample of 91 anesthesia providers: 36 Certified Registered Nurse Anesthetists (CRNAs), 48 student registered nurse anesthetists (SRNAs), and 7 anesthesiologists. We applied a known volume of moulage (theater) blood to items at 4 stations and asked each participant to estimate the amount of blood present at each station. Descriptive and inferential statistical analyses were performed. Multivariate regression analysis was conducted to evaluate the association of estimation errors with covariates (provider training, gender, ethnicity, years of education, and years of anesthesia experience). We found no difference in the mean error of blood loss estimation based on provider training, gender, ethnicity, education, or experience. Although no statistically significant differences in blood loss estimations existed among provider groups, CRNAs had smaller mean errors than anesthesiologists in all 4 stations and smaller mean errors than SRNAs in 3 of 4 stations. Accuracy of estimating blood loss, measured by mean error, was not related to type of provider training, years of education or experience, gender, or ethnicity. Anesthesia providers may not estimate blood loss accurately.