The purpose of this study was to locate the common discrepancy sites in a periodontal examination by new student dentists in a dental school setting and to evaluate student progress after one year of clinical training. Sixty-nine patients were enrolled in the initial phase of this study. Periodontal probing examinations were performed by both dental students and calibrated faculty members. A total of 9,171 sites were probed. Student-faculty agreement was then determined for each individual probing site. Frequency of agreement and average variance of agreement were calculated for each individual site probed. An identical procedure was conducted on thirteen patients by dental students after each had received one year of clinical training. A total of 1,991 sites were probed. Students new to the clinic had a significantly higher frequency of discrepancy in molars of all quadrants, with a trend of highest discrepancy shifting from mesial to distal sites when moving posteriorly in the posterior region. After one year of experience, there was a significant decline of discrepancy in all regions examined. More preclinical emphasis must be placed on proper probing technique to ensure accurate probing depths upon entry into the clinical setting.