Urinary tract infections (UTIs) represent a recurrent health problem especially for women. More than 50% of women will suffer from a UTI at least once in their lifetime. Cranberries have long been used for their beneficial effects in preventing symptomatic UTIs in several published studies. However, cranberry products used in these clinical studies do not indicate the amount of active ingredients delivered that help to prevent UTIs. Therefore, a dose-dependent study was designed to understand the impact and safety profile of a standardized cranberry product (Proanthocyanidins Standardized Whole Cranberry Powder,PS-WCP) on reducing the recurrences of symptomatic UTI in culture-positive subjects. A 90-day randomized clinical trial including an untreated control group with a total of 60 female subjects between 18-40 years of age was conducted. Study subjects were randomly selected and assigned to three groups including an untreated control group (n=16), a low dose (500 mg daily, n=21) and a high dose (1000 mg daily, n=23) treatment group. The safety of PS-WCP was assessed by evaluation of biochemical and hematological parameters on days 10, 30, 60 and 90 during the study, comparing the values with those at the baseline. Occurrence of UTI at baseline and during the follow-up period was characterized by the presence of symptoms and Escherichia coli in the culture of urine samples. The statistical analysis used was ANOVA. At the end of the 90-day treatment period, no significant changes were observed in the hematological and serum biochemical parameters. At the end of the study, change in the presence of E. coli in the untreated control group was not significant (p=0.7234), whereas, there was significant reduction (p<0.05) in the subjects positive for E. coli in both the high dose and low dose treatment groups, compared to baseline evaluation. Symptomatic relief was also reported in the low and high dose treatment groups, while none was reported by subjects in the untreated control group. In conclusion, PS-WCP was effective in safely reducing the number of E. coli positive subjects at both the 500 mg and 1000 mg dose levels and in ameliorating the symptoms of UTI in these subjects. Therefore, a daily dose of 500 mg or 1000 mg of PS-WCP may be considered as an adjunct to antibiotic prophylactic therapy against recurrent UTIs.