Numerous studies have been performed to identify potential risk factors for CP/CPPS and IC. However, few studies have been done to identify predictors of disease severity. A total of 174 men with CP/CPPS and 111 women with IC completed questionnaires to quantify symptom severity and identify demographic, medical and psychosocial characteristics. Symptom severity was assessed with the National Institutes of Health CPSI in men, and the O'Leary-Sant ICSI and problem index in women. Univariate and multivariate analyses were performed to identify characteristics predictive of worse symptoms. The mean National Institutes of Health CPSI score in men was 15.32, and the mean O'Leary-Sant ICSI and problem index in women was 19.17. The most commonly reported comorbidities were allergies, sinusitis, erectile dysfunction and irritable bowel syndrome in men, and allergies, urinary incontinence, sinusitis and irritable bowel syndrome in women. In the 2 sexes self-reported urinary frequency and urgency, worse depression scores and lower education level were independent predictors of worse symptom severity. In men additional independent predictors were self-reported pelvic pain, fibromyalgia and previous heart attack, and in women an additional independent predictor was postmenopausal status. There are several common medical conditions associated with urological pelvic pain syndromes in men and women. Few of them were predictive of symptoms severity in this analysis. Self-reported pelvic pain symptoms, education and depression severity were the factors most strongly predictive of symptom severity in patients with CP/CPPS and IC.