Many serious and fatal infections with urogenital mycoplasmas in immunocompromised patients have been reported. M. genitalium is recognized as a cause of male urethritis and other common genitourinary diseases. The aim of the study was to estimate prevalence of urogenital mycoplasmas which can cause complications in men with common genitourinary diseases. Study included 85 men with genitourinary tract carcinoma (n = 35), urolithiasis (n = 36), and BPH (benign prostatic hyperplasia) (n = 14). The control group consisted of 50 healthy men. FVU (first void urine) samples were examined by PCR for the presence of urogenital mycoplasmas DNA. Occurrence of urogenital mycoplasmas was significantly more common in study group compared with control 24/85 (28.2%) and 7/50 (14%), respectively (p = 0.05). In men with urolithiasis, positive results for mycoplasmas DNA were significantly more frequent than in control: 33.3% vs. 14% (p < 0.05). In patients with urolithiasis DNA of U. urealyticum was most often found, while in the genitourinary carcinoma and BPH groups, U. parvum was more frequent. Incidence of M. fermentans was also significantly higher in the urolithiasis group vs. control (p = 0.03). A higher percentage of positive results for urogenital mycoplasma DNA in study group has been found. Further studies are required to confirm the role of urogenital mycoplasmas in the development of infectious complications among patients with urolithiasis, genitourinary carcinoma, and BPH.