Abstract: Objective To investigate the effect of the irrigating solution of Sihuang (ISSH) given after endoscopic surgery for chronic sinusitis and nasal polyps. Methods ISSH was used to irrigate the operated sinus cavity for 4 weeks in 109 patients with chronic sinusitis and/or polyps treated by endoscopic surgery, and 0.9% normal saline (NS) was given in the same manner in another 109 patients receiving ISSH for similar problems, and the effects of the irrigating solutions was compared. Before and 3 months after the surgery, respectively, 32 patients with sinusitis were selected from each group for saccharin test. The mucosa in the ostiomeatal complex region was examined by electron microscopy in 6 patients before, two weeks and one month after surgery, respectively. Results The total effective rate was not significantly different between the two groups, but the postoperative morphological and functional recovery of the nasal mucosa occurred earlier in ISSH than in NS group (P<0.05). The level of SIgA was similar between the two groups before treatment (P>0.05), whereas after ISSH treatment, the SIgA level was significantly elevated in the treated group. Mucociliary transport rate was similar between ISSH and NS groups before the surgery (3.14±1.05 mm/min vs 3.31±1.09 mm/min, P>0.05), but 3 month after the surgery, the mucociliary transport rate increased to 6.09±2.63 mm/min in ISSH group and 5.04±1.22 mm/min in NS group, showing significant difference between them. Under electron microscope, the cilia of the epithelial cells were found exfoliated preoperatively but regularly arranged after the surgery, presenting the "9+2" architecture of the microtubule. Conclusion ISSH used after operation can improve the therapeutic effect of endoscopic surgery for chronic sinusitis and/or nasal polyps.