Objective: The study was done to evaluate flowmetry parameters, bladder capacity and postvoiding residual volume (PVR) in patients with chronic bacterial prostatitis/category II according to the National Institute of Health (NIH) categorization of prostatitis syndromes (CBP/Cat.II). Subjects and Methods: A prospective study of 42 patients with chronic CBP/Cat.II was undertaken. Clinical evaluation and the standard four-glass test with direct microscopy and culture were done for all patients. Flowmetry parameters and PVR were measured. Two groups were compared to the CBP/Cat.II group; a control age matched 42 males without lower urinary tract symptoms and 279 patients with prostatodynia/non-inflammatory chronic pelvic pain (CPP/Cat.IIIB). Results: All the three groups had similar age. The CBP/Cat.II and CPP/Cat.IIIB patients had similar duration of symptoms. In CBP/Cat.II maximum flow rate (Q(max)), average flow rate (Q(ave)), and voided volume (V-ura) were 12.8 +/- 5.9 ml/s, 7.4 +/- 3.4 ml/s, and 238.9 +/- 110.8 ml. These were significantly less than those for normal controls (21.3 +/- 4.2 ml/s, 12.2 +/- 3.4 ml/s, and 381.3 +/- 144.4 ml). The flowmetry findings in CBP/Cat.II group did not show statistically significant differences from those for CPP/Cat.IIIB group (Q(max), Q(ave), and V-ura were 11.3 +/- 5.3 ml/s, 6.6 +/- 2.0 ml/s, and 230.5 +/- 88.8 ml). In CBP/Cat.II group, patients with Q(max) < 15 ml/s (25/42) had statistically significant longer duration of symptoms (33.6 +/- 19.3 compared to 13.1 +/- 6.3 months). Conclusion: In this study, CBP/Cat.II patients had significantly lower flowmetry parameters compared to matched age normals. The flowmetry parameters in this group were found similar to those in a group of CPP/Cat.IIIB patients. Voiding dysfunction in CBP/Cat.II nmay contribute to the longer duration of symptoms. (C) 2002 Elsevier Science B.V. All rights reserved.