A pilot study of twenty-four hour urine iodine excretion was carried out in 34 adults who were employees (or their spouses) of Maricopa Medical Center and residents of the Phoenix area. Based on previous estimations, our expectation was that urine iodine excretion values should be high. The mean value was 219 +/- 25 microg/day in the first collection and 229 +/- 23 microg/day when the collection was repeated 4 months later. The results support an adequate amount of iodine in the diet for the group. However, they indicate an iodine intake lower than what previously published studies had estimated for this area. It is not clear whether these results reflect a regional or national trend of decreased dietary iodine intake or changes in dietary iodine intake limited to the cohort studied. These data indicate a need for further study to clarify this finding in view of possible clinical implications resulting from changes in iodine intake.