As many as one in three people worldwide have anemia, with young children at increased risk of both disease and complications. In settings without clinical laboratories, portable hemoglobinometers serve important roles in diagnosing anemia and estimating prevalence. Here, we assess the validity of two such point-of-care devices-the HemoCue Hb201 and the HemoCue Hb301-relative to the international reference standard, the cyanmethemoglobin method. In total, 428 children ages 6-60 months were recruited at health posts in Lima, Peru, and venous and capillary blood samples were collected from each participant. Venous blood was assessed with the cyanmethemoglobin method, whereas capillary blood was assessed using the Hb201 and the Hb301; 16.1% of participants were found to have anemia using the cyanmethemoglobin method. Both the Hb201 (43.7%) and the Hb301 (20.6%) overestimated this prevalence, with the former reaching statistical significance (P <0.0001 and P = 0.11, respectively). Both devices also tended to underestimate hemoglobin concentration, with the Hb201 (mean difference = -0.99 g/dL; percentage error = -8.1%) being appreciably less accurate than the Hb301 (mean difference = -0.35 g/dL; percentage error = -2.7%). Areas under the curve for the Hb201 (0.92) and the Hb301 (0.93) were statistically similar (P = 0.28); however, the Hb201 incorrectly classified 29.4% of participants compared with 11.0% for the Hb301. Both devices had more false positives than false negatives. In conclusion, the Hb301 was found to be significantly more accurate than the Hb201 at measuring hemoglobin, diagnosing anemia, and estimating anemia prevalence.