The aim of this study was to evaluate the frequency of male accessory gland infection (MAGI) in patients with chronic bacterial prostatitis (CBP) plus irritable bowel syndrome (IBS) and to compare the sperm parameters of patients with or without MAGI. In addition, another objective of this study was to evaluate the ultrasound characterization of the anatomical space between the posterior wall of the prostate and the anterior wall of the rectum using transrectal ultrasonography. Fifty consecutive patients with the following criteria were enrolled: 1) infertility, 2) diagnosis of CBP, and 3) diagnosis of IBS according to the Rome III criteria. The following 2 age-matched control groups were also studied: infertile patients with CBP alone (n = 56) and fertile men (n = 30) who had fathered a child within the previous 3 months. Patients and controls underwent an accurate patient history; administration of the National Institutes of Health-Chronic Prostatitis Symptom Index and the Rome III questionnaires for prostatitis and IBS, respectively; physical examination; semen analysis; and transrectal ultrasound evaluation (limited to patients with CBP and IBS or CBP alone). A significantly higher frequency of MAGI was found in patients with CBP plus IBS (82.0%) compared with patients with CBP alone (53.6%) or fertile men (0%). The presence of MAGI in patients with CBP plus IBS was associated with a significantly lower sperm concentration, total number, and forward motility, and with a higher seminal leukocyte concentration compared with patients with CBP alone and MAGI. Sperm normal morphology was similar in the groups of patients. All sperm parameters did not differ significantly in both groups of patients without MAGI. With ultrasound evaluation, a significantly higher frequency of dilatation of prostatic venous plexus was found in patients with CBP plus IBS (75%) compared with patients with CBP alone (10%). Patients with CBP plus IBS had a significantly higher frequency of MAGI compared with patients with CBP alone. This was associated with worse sperm parameters and, hence, poorer reproductive prognosis. We suggest searching for the presence of IBS in patients with prostatitis syndrome, in particular when CBP and/or worse sperm parameters are present. Finally, this is the first observation on ultrasound examination of the anatomical space between the posterior wall of the prostate and the anterior wall of the rectum reported in patients with CBP and IBS. Further studies should clarify the meaning of the ultrasound findings.