OBJECTIVES To assess urologists' and patients' compliance with treatment recommendations based on a prostate cancer risk calculator (RC) and the reasons for non-compliance. To assess the difference between patients who were compliant and non-compliant with recommendations based on this RC. PATIENTS AND METHODS Eight urologists from five Dutch hospitals included 240 patients with prostate cancer (PCa), aged 55-75 years, from December 2008 to February 2011. The urologists used the European Randomized Study of Screening for Prostate Cancer RC which predicts the probability of potentially indolent PCa (P [indolent]), using serum prostate-specific antigen (PSA), prostate volume and pathological findings on biopsy. Inclusion criteria were PSA <20 ng/mL, clinical stage T1 or T2a-c disease, <50% positive sextant biopsy cores, <= 20 mm cancer tissue, >= 40 mm benign tissue and Gleason <= 3 + 3. If the P(indolent) was >70%, active surveillance (AS) was recommended, and active treatment (AT) otherwise. After the treatment decision, patients completed a questionnaire about their treatment choice, related (dis) advantages, and validated measurements of other factors, e. g. anxiety. RESULTS Most patients (45/55, 82%) were compliant with an AS recommendation. Another 54 chose AS despite an AT recommendation (54/185, 29%). The most common reason for noncompliance with AT recommendations by urologists was the patient's preference for AS (n = 30). These patients most often reported the delay of physical side effects of AT as the main advantage (n = 19). Those who complied with AT recommendations had higher mean PSA levels (8 vs 7 ng/mL, P = 0.02), higher mean amount of cancer tissue (7 vs 3 mm, P < 0.001), lower mean P(indolent) (36% vs 55%, P < 0.001), and higher mean generic anxiety scores (42 vs 38, P = 0.03) than those who did not comply. CONCLUSIONS AS recommendations were followed by most patients, while 29% with AT recommendations chose AS instead. Although further research is needed to validate the RC threshold, the current version is already useful in treatment decision-making in men with localized PCa.