Urinary tract infections (UTIs) are the most common bacterial infections in women, and many patients experience frequent recurrence. The aim of this report is to introduce an on-going prospective phase II clinical trial performed to evaluate the preventive effectiveness of Lactobacillus vaginal suppositories for prevention of recurrent cystitis. Patients enrolled in this study are administered vaginal suppositories containing the GAI 98322 strain of Lactobacillus crispatus every 2 days or 3 times a week for one year. The primary endpoint is recurrence of cystitis and the secondary endpoints are adverse events. Recruitment began in December 2013 and target sample size is 20 participants.