We evaluated the operation of the Yellow Springs Instrument Co. (YSI) glucose analyzer (model 23A) by clinical nurses for the measurement of blood glucose in the intensive care nursery. In vitro performance was determined with the use of aqueous standards; with a 2-point calibration of 0.0 and 200 mg/dl, a precision of better than 1.0% of each standard (25, 50, 100, 200 mg/dl) was achieved, and the linearity was excellent (Y = 0.99X - 0.49, r = 0.99). The YSI correlated well with a manual spectrophotometric glucose oxidase method (r = 0.99) and the Kodak Ektachem analyzer (r = 0.98) using human umbilical cord blood samples. Five trained clinical nurses performed all YSI and glucose reagent strip analyses, including all in vitro and patient samples. Four reagent strip methods were compared with the YSI from 104 neonatal heel-stick blood samples: Glucometer II with memory (r = 0.73), Glucostix (r = 0.74), Dextrostix (r = 0.70), and Chemstrip bG (r = 0.83). We conclude that clinical nurses can and do learn to use the YSI with excellent precision and that the YSI represents an improved method for measuring glucose concentrations in the newborn intensive care nursery.