The urodynamic catheter and its transducer play a significant role in the performance of good urodynamic studies. The fluid-filled (perfusion) catheter with its external strain gauge transducer and the microtransducer catheter with a transducer built directly into the catheter are the two most prevalent catheters used in urodynamic studies today. Either functions differently with regard to how pressures are measured during testing. Both are unique with regard to their requirements for handling and management during testing. Proper transducer calibration, maintenance of standardized reference levels, and attention to catheter zeroing procedures as outlined by the International Continence Society are vital to good study technique and quality testing results. When used in a manner consistent with the catheter's performance characteristics, study error is minimized and meaningful clinical data can be obtained.