OBJECTIVES: Individuals with hyperlipidemia are at risk for CHD, hypertension and diabetes. This study examined the likelihood of receiving prescription therapy based on patient diagnoses, demographics and other factors. METHODS: The study design was retrospective covering January 2000 - December 2002. It encompassed 15,000 electronic medical records from primary care practices in eight States. Patients with lipoid disorders were identified by ICD-9 diagnoses. Treatment patterns and laboratory data were evaluated vs. NCEP ATP III Guidelines. RESULTS: On average, 23.4 % of patients eligible for treatment according to the Guidelines were prescribed cholesterol lowering drugs. Of those, 40.5% of patients (95% CI 39.6% - 41.3%) had prescription therapy without a hyperlipidemia diagnosis. In each of these cases, one or more co-morbid diagnoses for CHD risk were present. The likelihood of treatment for patients < 45 years was 1.37 times lower (p<0.001) than older patients in the "official" risk age for CHD (55-64 years). The probability of treatment for men was higher than for women (OR 1.11 p <0.01). There was no significant difference in treatment frequency for Caucasians vs. blacks. The likelihood of treatment for patients with documented hyperlipidemia was 3.86 times higher than for those without a diagnosis (p <0.0001). The likelihood of treatment for patients with CHD was 1.6 times higher (1.59 -1.89) than for patients without. CONCLUSIONS: In patients diagnosed with lipoid disorders and at risk for CHD, the use of cholesterol lowering medication appears to be relatively low compared to that recommended by the NCEP ATP III Guidelines. In those patients who are prescribed cholesterol lowering medication without documented hyperlipidemia, the presence of CHD risk factors appear to be a major consideration. Possible reasons for a relatively low level of prescribing include undocumented treatment by life style changes, lack of awareness of NCEP guidelines by physicians, economic constraints, and/or other factors.