Analysts frequently have used health maintenance organization (HMO) st
affing patterns as a yardstick for estimating national clinical workfo
rce requirements. Based on a nationwide survey of fifty-four staff- an
d group-model HMOs, the largest sample yet used in an analysis of this
type, this DataWatch examines physician-to-member ratios, the use of
nonphysician providers, and HMOs' methods of estimating clinical staff
ing needs. Overall physician staffing ratios and primary care physicia
n staffing ratios closely resemble those reported in previous studies,
but they exhibit wide variability and are strongly correlated with HM
O size. Although caution should be exercised when using HMO staffing r
atios in projections of physician workforce requirements, the ratios d
escribed here support projections of a specialty physician surplus.