OBJECTIVE: To examine the impact of implementing Bethesda 2001 in one laboratory. STUDY DESIGN: A computer search identified all cervicovaginal specimens evaluated between July 2001 and June 2002. Bethesda 2001 was implemented on January 1, 2002. The rates of specimen adequacy and the frequency of each diagnostic category 6 months before and 6 months after the implementation of Bethesda 2001 were compared. RESULTS: A total of 21,332 cervicovaginal specimens were evaluated during the study period. During the first 6 months, 10,695 specimens were examined; 40% were liquid-based preparations. During the next 6 months, 10,367 specimens were examined; 60% were liquid-based preparations. Prior to the implementation of Bethesda 2001, the percentages of each category were as follows: 74.99% within normal limits, 7.10% reactive/reparative cellular changes (R/R), 10.29% atypical squamous cells (ASC), 0.24% atypical glandular cells (AGC), 3.45% low grade squamous intraepithelial lesion (LSIL), 3.44% high grade squamous intraepithelial lesion (HSIL) and 0.73% unsatisfactory. In addition, 19.00% were classified as "satisfactory but limited by" (SBLB). Following the implementation of Bethesda 2001, the percentages of each category were as follows: 80.09% negative for intraepithelial lesion and malignancy including 6.94% with the qualifier R/R, 10.32% ASC, 0.27% AGC, 4.54% LSIL, 3.44% HSIL and 0.81% unsatisfactory. In addition, 17.40% were satisfactory with a quality indicator (SAT with QI). The incidence of reporting benign endometrial cells in patients over age 40 was the same for both periods. There was a significant decrease in the percentage of specimens classified as SAT with QI when compared to that of specimens classified as SBLB. A statistically significant increase in the percentage of specimens was noted in the category LSIL (P≤.001) and satisfactory (.005) after implementing Bethesda 2001. No significant changes were noted in other categories. CONCLUSION: Our laboratory experienced some changes in the laboratory statistics of reporting gynecologic cytology after the implementation of Bethesda 2001. Continuous monitoring of reporting trends is indicated to clearly understand the impact of Bethesda 2001 on laboratory statistics.