Latex reagents for HCG obtained from commercially available pregnancy test kits were adapted for use on Instrumentation Laboratory's Multistat III Plus centrifugal analyzer. The clearance rate of an agglutinating reaction mixture can be measured by absorbance over a time period of 15 min. The automated system has a sensitivity of less than 5 mIU HCG/ml in buffer or urine with a range of up to 100 mIU HCG/ml. Statistical analyses on urine samples indicated CVs of between 7.6% and 10.7% for within-run precision and between 6.8% and 10.8% for between-run precision. The correlation between the centrifugal latex agglutination method and two commercially available RIAs was found to be about 87%.