Four floor pen studies were carried out to evaluate the effects of nicarbazin (NIC) administration on blood glucose concentrations and the onset of hypoglycemia in broiler chickens. All tests involved continuous NIC feeding at 0, 100, or 125 ppm to 28 days of age. In each study, birds were reared at both standard environmental temperatures and at 3 C below this level. In addition, two studies were conducted in the presence of coccidial infection and two were carried out in noninfected broilers. At 26 days of age in each test, two birds per pen were bled by puncture of the brachial vein, and whole blood glucose concentrations were determined. Results indicated that the administration of NIC to broilers for 26 days had no effect on blood glucose concentrations, although graded levels of NIC tended to increase these values. In addition, no evidence of hypoglycemia was recorded in any of the trials. In a similar fashion, blood glucose was unaffected by environmental temperature and coccidial challenge. These findings support previous work showing that NIC administration does not influence blood glucose levels and indicate that the product is not involved when field diagnoses use reduced blood glucose and hypoglycemia as indicators of production anomalies.