Objective: The main aim of this research was to determine specific causes of acute and chronic prostatitis and to establish the difference between causes among the examinees younger than 35 and older than 35. Study design: This study is designed as a cross-sectional study. Participants and methods: The examinees in this research are patients with acute and chronic prostatitis of the Department of Urology of the Clinical Hospital Centre Osijek who were treated for acute and chronic prostatitis during the period between 1 May 2017 to 1 May 2018 with positive ejaculate or urine findings. The data in this research are secondary, taken from the hospital documentation, and the variables were age, ejaculate and urine Results: Of the total number of men, 13 (27%) are at the age of under 35 while 36 (73%) are older than 35. In ejaculate analysis report Escherichia coli was the most common among 12 (25 %) men, significantly more at the age below 35 while Enterococcus faecalis was significantly more common among older men. Regarding urine findings, among 46 (94 %) men it was sterile while other three had Escherichia coli, Klebsiella pneumoniae and Enterobacter spp. Respectively there is no significant difference in urine findings according to the age of men. According to symptoms, most examinees, 49 (100%) of them are with symptoms caused by urethra and urinary bladder disorder, 33 (67 %) men have symptoms caused by prostate disorder, and 25 (51 %) have symptoms such as headache, weakness, fever, chills, shivering. There is no significant difference in symptoms between younger and older men. Conclusion: More frequently, cause of acute and chronic bacterial prostatitis is Enterococcus faecalis, and more rarely sexually transmitted bacteria.