The health problems of 2,136 patients randomly selected from 8,905 patients seen by 356 family nurse practitioners around the U.S.A. were analyzed. Primary diagnoses were reported on all patients using an adapted H-ICDA/ICHPPC classification. This system allowed for 18 diagnostic categories and 115 diagnoses relevant to primary care. The ten most frequent diagnostic categories were reported and analyzed as to certainty and status (old or new diagnosis). Analysis of diagnostic certainty revealed areas where FNPs felt most accurate. Reporting both diagnoses and diagnostic categories allowed greater understanding of the health problems presented to family nurse practitioners in primary care. This comprehensive data bank of patient care problems adds another dimension to the study of primary care and is a useful tool in further family nurse practitioner research and in curriculum development.