BACKGROUND: Endoanal ultrasound is widely used for the detection of external and internal anal sphincter defects in patients with fecal incontinence. Recently, 3-dimensional transperineal ultrasound has been introduced as a noninvasive imaging method for the detection of these sphincter defects. OBJECTIVE: This study was designed to assess agreement between 3-dimensional transperineal ultrasound and 2-dimensional endoanal ultrasound regarding the detection of anal sphincter defects in women with fecal incontinence. DESIGN: This study was designed as a prospective observational study. SETTINGS: The study took place in a university hospital. PATIENTS: Between October 2008 and June 2009, all women with concerns of fecal incontinence underwent 2-dimensional endoanal ultrasound as well as 3-dimensional transperineal ultrasound. MAIN OUTCOME MEASURES: The main outcome measures are the presence of external and internal anal sphincter defects. RESULTS: Fifty-five patients were included. External and internal anal sphincter defects were observed with 2-dimensional endoanal ultrasound in 27 (49%) and 15 (27%) patients. Three-dimensional transperineal ultrasound detected an external and internal sphincter defect in 19 (35%) and 16 (29%) patients. The Cohen kappa coefficient for the detection of external (kappa = 0.63) and internal (kappa = 0.78) anal sphincter defects was good. LIMITATIONS: This study's limitations include the absence of a surgical examination as the reference standard in the determination of sphincter defects. CONCLUSION: This study shows good agreement between 3-dimensional transperineal ultrasound and 2-dimensional endoanal ultrasound regarding the detection of anal sphincter defects. Based on these data, 3-dimensional transperineal ultrasound might be considered as a valuable alternative noninvasive investigation method.