In a context where there is evidence that not every patient with low risk prostate cancer needs to be treated from the start, active treatments are expensive and public health care systems need to save money, studies on cost-effectiveness are a priority. To elaborate this article, we reviewed the publications on cost and cost-effectiveness of localized prostate cancer treatments that include active surveillance. In patients with low risk localized prostate cancer active surveillance is more cost-effective than active treatment. With time active surveillance may be more expensive than brachytherapy or radical prostatectomy. The frequency of prostatic biopsies and the percentage of conversions to active treatment will be determinant in final costs of active surveillance.