The Collaborative Ambulatory Research Network, a voluntary subset of 550 ACOG Fellows from 130 practices, responded to a self-administered study regarding hepatitis B, gestational diabetes, neutral tube defects, and trisomy 21 office screening techniques. Hepatitis screening was performed by all practices reporting, with 95% of patients being tested; however, only 55% (six of 11) of newborns at risk received treatment. O'Sullivan screening (50-g glucose load with a 1-hour postload glucose) was performed for all obstetric patients by 94% of the practices, regardless of risk factors. Two-thirds of these practices used ≥140 mg/dL for further screening, and 34% used glucose levels in the 130-135 mg/dL range. Ninety-two percent of respondents report offering maternal serum α-fetoprotein screening for neural tube defects. Eighty-four percent of respondents offered serum screening for trisomy 21 to women <35 years of age, with 68% using a double- or triple- screen technique. Women ≥35 years of age had serum screening offered by 87% of the practices; however, 41% offered serum screening only if amniocentesis was declined when offered for age risk alone. Practitioner appreciation of the relatively high initial positive rate and poor specificity of serum screening was underappreciated by a large number of respondents.