Background. Glomerular upregulation of miR-193a has been detected in primary focal segmental glomerulosclerosis (FSGS) but not in other glomerular diseases. We aimed to isolate exosomes from urine of children with primary FSGS and to assess the diagnostic potential of urinary exosomal miR-193a for primary FSGS. Methods. The first morning urine samples were collected from children with primary FSGS (n = 8) and minimal change disease (MCD, n = 5). Isolated urinary exosomes were confirmed by electron microscopy and Western blotting. Urinary exosomal microRNA was extracted, and the expression levels of exosomal miR-193a were quantified by real-time PCR. The diagnosis value of urinary exosomal miR-193a levels for primary FSGS was evaluated by ROC analysis. Results. The isolated vesicles were qualitatively compatible with exosomes. The levels of urinary exosomal miR-193a were significantly higher in children with primary FSGS than those in children with MCD. Moreover, the area under the ROC for the diagnosis of primary FSGS using urinary exosomal miR-193a was 0.85. Conclusions. A significant increase in the levels of urinary exosomal miR-193a in primary FSGS patients compared to those in MCD ones was observed. This study suggests that urinary exosomal miR-193a may be a new noninvasive biomarker for the diagnosis of primary FSGS.