Purpose: Evaluation of clinical and paraclinical symptoms of adult cryptorchidism operated at Viet Duc hospital. Patients and methods: Adult patients from 18 years old were diagnosed as cryptorchidism and operated at Urology department of Viet Duc hospital during the period from January 2011 to July 2013. Oinical and para-clinical signs were analyzed. Results: the authors studied 144 patients including 97 patients with unilateral undecended testis and 47 patients with bilateral undecended testes. Thus, a total of 191 testes were studied. The mean [range] age was 26.6 + or - 5,7 [18-46] years. The higher the testis, the more atrophic testis was (p 0.05). The rate of severely atrophic testes was 82.2 percent (157 testes). The serum testosterone level in patients with bilateral cryptorchidism was 13.0 + or - 6.3 nmol/I, less than that in patients with unilateral cryptorchidism (16.4 + or - 7.4 nmol/I) (p0.05). The semen volume and sperm concentration in patients with bilateral undescended testes were less than those in patients with unilateral undescended testis (p0.05). Conclusion: Despite of undifficult diagnosis, cryptorchidism is still treated too late. Patient's clinical and para-clinical signs reveal a poor prognosis, especially reproductive possibility.