PURPOSE: To evaluate the incidence rate and risk factors for periprosthetic fracture after total knee replacement (TKR). MATERIALS AND METHODS: We carried out a retrospective case-control study of 596 patients (951 knees) who underwent TKR between 1999 and 2006 and who were followed up over 36 months. We classified patients into group I (study group) and group II (control group). We subdivided risk factors as pre-operative, intra-operative, and post-operative factors. Age, osteoporosis, revision arthroplasty, CVA, and alcohol dependence were categorized as pre-operative factors; anterior femoral notching and prosthetic types (mobile, fixed, and load-bearing) were considered intra-operative factors; and post-operative activity level was classified as a post-operative factor. We obtained information from the patients' charts, X-ray film, and telephone interviews. RESULTS: The overall incidence rate was 2.25%; 3 patients were male, and 18 were female (14.28% and 85.72%, respectively). Old age (p<0.01, odds ratio=1.14), osteoporosis (p=0.01, odds ratio=4.74), revision arthroplasty (p=0.01, odds ratio=7.46), CVA (p=0.02, odds ratio=8.55), and alcohol dependence (p=0.03, odds ratio=44.54) were statistically significant among the pre-operative factors. Among the intra-operative factors, anterior femoral notching (p<0.01, odds ratio=11.74) was significant, and continued heavy labor (p<0.01, odds ratio=8.14) was significant among the post-operative factors. CONCLUSION: We concluded that old age, osteoporosis, revision arthroplasty, comorbidity related with falling down, anterior femoral notching, and continued heavy labor were associated with periprosthetic fracture after TKR.