In a series of 3 studies, indirect blood pressure measurements were obtained to define normal variance, identify hypertension, and estimate the prevalence of hypertension in apparently healthy dogs. In part 1, we measured values in 5 clinically normal dogs twice weekly for 5 weeks in a home setting. Mean +/- SD systolic arterial pressure (SAP) and diastolic arterial pressure (DAP) was 150 +/- 16 and 86 +/- 13 mm of Hg, respectively. The DAP significantly (P less than 0.01) decreased with repeated measurements over the 5-week period. In part 2, we assessed the variation between blood pressures measured in a clinic vs those measured in the home. Within a 2-week period, measurements were obtained from 10 clinically normal dogs in a private veterinary clinic and again in their home. Significant differences were not observed between clinic and home measurements of SAP and DAP; however, heart rate was significantly (P less than 0.05) higher in the clinic. In part 3, SD about the SAP and DAP mean values were determined in 102 clinically normal dogs. Canine hypertensive status was determined, using statistical methods and data from 102 clinically normal dogs. Values of SAP greater than 202 mm of Hg and DAP greater than 116 mm of Hg were determined to be 2 SD beyond the mean and, therefore, were interpreted to be hypertensive. Approximately 10% of the 102 apparently healthy dogs measured in this study were considered hypertensive on the basis of these criteria. In addition, a border zone of suspected hypertension was estimated, using the mean + 1.282 SD. The SAP border zone was between 183 and 202 mm of Hg, whereas the DAP border zone was between 102 and 113 mm of Hg. Of the 102 dogs, 12 had values within these zones of suspected hypertension.