[Comparison between the results of ICSI with fresh and with frozen-thawed sperm obtained by PESA to treat azoospermia]. 
Retrospective study of the results of ICSI (intracytoplasmic sperm insemination) with frozen sperm obtained by PESA (percutaneous epididymal sperm aspiration) was performed in 27 patients.  With conventional freezing method, sperm from diagnosing PESA and the remaining motile sperm after treating cycle were frozen.  After frozen-thawed and ICSI process, fertilization rate, implantation rate, clinical pregnancy rate were compared and other outcomes including pregnant combinations and parameters of newborns of experimental group (which used frozen-thawed sperm) and control group (which used fresh PESA sperm) were analyzed respectively.  One hundred and sixty three and 1 157 oocytes of stage M II were injected respectively in the experimental group (15 cycles) and control group (100 cycles), and fertilization rate of experimental group was prominently higher than that of control group (84.05% vs 73.29%, P < 0.05), while implantation rate and clinical pregnancy rate were of no difference from the control, respectively (23.07% vs 15.73%; 53.33% vs 37.00%, P > 0.05).  The differences in newborn's weights between two groups were of no statistical significance (P > 0.05).  In the experimental group, eight clinical pregnancies were achieved including 5 live deliveries and 3 ongoing pregnancies, 37 clinical pregnancies including 30 deliveries with only 1 fetal death, 3 ongoing pregnancies and 4 abortions in the control group.  Neither vital pregnant combinations nor neonate malformations were found in both groups.  ICSI using frozen-thawed sperm obtained by PESA is an economic effective and safe method to treat azoospermia.  Recovering rates of frozen sperm form PESA should be further increased.