Background: Men diagnosed with localized prostate cancer (PCa) on active surveillance (AS) have shown to cope with anxiety caused by living with an ‘untreated cancer’ and different factors can influence the tolerance level for anxiety in these patients. The present study analyzes Italian (Milan) and Dutch (Rotterdam) men prospectively included in the Prostate cancer International Active Surveillance (PRIAS) trial, aiming to explore whether socio-demographic factors (i.e. age, relationship status, education, nationality) may be relevant factors in conditioning the level of anxiety at AS entry and over time. Methods: Italian and Dutch men participating in the IRB-approved PRIAS study, after signing an informed consent, filled in the Memorial Anxiety Scale for PCa (MAX-PC) at multiple time points after diagnosis. A linear mixed model was used to assess the relationship between the level of patient’s anxiety and time spent on AS, country of origin, the interaction between country and time on AS, patients’ relationship status and education, on PCa anxiety during AS. Results: 823 MAX-PC questionnaires were available for Italian and 307 for Dutch men, respectively. Median age at diagnosis was 64 years (IQR 60–70 years) and did not differ between countries. On average, Dutch men had a higher total MAX-PC score than Italian men. However, the level of their anxiety decreased over time. Dutch men on average had a higher score on the PCa anxiety sub-domain, which did not decrease over time. Minimal differences were observed in the sub-domains PSA anxiety and fear of recurrence. Conclusion: Significant differences in PCa anxiety between the Italian and Dutch cohorts were observed, the latter group of men showing higher overall levels of anxiety. These differences were not related to the socio-demographic factors we studied. Although both PRIAS-centers are dedicated AS-centers, differences in PCa-care organization (e.g. having a multidisciplinary team) may have contributed to the observed different level of anxiety at the ...