We report the results of a prospective study with the pollen extract, Cernilton N, in a dose of 1 tablet tid for 6 months for the treatment of chronic prostatitis syndrome in 90 patients. The factors documented before and after 3 and 6 months' treatment were digital rectal examination (DRE) of the prostate, uroflowmetry, bacterial studies, leucocyte counts in urine and measurement of complement C3/coeruloplasmin in the seminal fluid. The patients were divided into 2 groups: those without associated complicating factors (CFs) (n = 72) and those with complicating factors, i.e. urethral strictures, prostatic calculi, bladder neck sclerosis (n = 18). In the group without CFs, 56 (78%) had a favorable response; 26 (36%) were cured of their symptoms and signs and 30 (42%) improved significantly with an increase in flow rate, a reduction in leukocyturia in the post-prostate massage urine (VB3) and a decrease in complement C3/coeruloplasmin in the ejaculate. In the patients with CFs only 1 patient showed a response. Complicating factors should be considered in patients who fail to respond to treatment within 3 months. Cernilton N was well tolerated by 97% of patients.