To determine the prevalence of excessively worn incisors (XSW) and periodontal disease (PD) in sheep in Dunedin City, Silverpeaks, Bruce and Clutha Counties, the incisors of 4049 mixed age ewes on 83 farms selected at random were examined between December 1983 and February 1984. Of these ewes, 14.9% had XSW (11.7% moderate, 3.2% severe), 13.7% had PD (10.5% moderate, 3.2% severe) and 71.4% had sound mouths. An additional 43 ewes had miscellaneous incisor faults, and these were excluded from the survey. Seventeen (20.5%) and 25 (30.1%) farms had >20% ewes with XSW and PD respectively. On two farms only did XSW and PD each occur at a prevalence of >15%. No association was found between the prevalence of XSW or PD and body condition score, breed or farm topography.