Objective To evaluate the efficacy and safety of intravesical instillation of sodium hya- luronate in relieving the symptoms of refractory non-bacterial cystitis.Methods Totally,20 patients(1 man and 19 women;mean age,47 years;age range,22-68 years)with refractory non-bacterial cystitis were included.Their disease course ranged from 1 month to 30 years.Of them,16 patients had the disease for more than 1 year.Instillation of sodium hyaluronate(50 ml solution of 40 mg HA)was performed intravesically in them for a total of 12 weeks(once a week for the first 4 weeks and once every 4 weeks for the succeeding 8 weeks).Follow-up visit ended at 16 weeks,when the patients filled in the symptom assessment scores(VAS on pain,frequency and urgency)according to the subjective evaluation.Therapeutic results were classified as(1)total response:symptom disappearance or relief by at least 90% of the symptom scores;(2)partial response:symptom relief by 50%-89%;(3)mild response:symptom relief by 49% or less;(4)no re- sponse:no improvement in symptom scores.Results Nineteen patients completed the 16-week follow-up with only 1 withdrawing.The average general symptom score decreased from 22.32?5.53 to 9.47?5.88 (P＜0.001);frequency score from 8.21?1.75 to 3.89v2.31(P＜0.001);urgency score from 7.47?2.14 to 3.37?2.14(P＜0.001);pain score from 6.63?3.47 to 2.21?2.74(P＜0.001).After 16 weeks,overall positive response rate(total+partial response)was 53%(10/19).No serious adverse effect occurred except for urethral irritation(25%,5/20),worsening of distending pain of the bladder(5%,1/20) and vertigo(15%,3/20)caused by the procedure itself.Conclusions For patients suffering from refrac- tory non-bacterial cystitis,intravesical instillations of sodium hyaluronate can significantly relieve the symp- toms and is safe and of good patient compliance.