Objective: To characterise the practice of active surveillance (AS) for men with low risk prostate cancer by examining the characteristics of those who commence AS, the rate of adherence to accepted AS follow-up protocols over 2 years, and factors associated with good adherence. Design, setting: Retrospective cohort study; analysis of data collected from 38 sites participating in the Prostate Cancer Outcomes RegistryeVictoria. Participants: Men diagnosed with prostate cancer between August 2008 and December 2014 aged 75 years or less at diagnosis, managed by AS for at least 2 years, and with an ISUP grade group of 3 or less (Gleason score no worse than 4 þ 3 ¼ 7). Main outcome measures: Adherence to an AS schedule consisting of at least three PSA measurements and at least one biopsy in the 2 years following diagnosis. Results: Of 1635 men eligible for inclusion in the analysis, 433 (26.5%) adhered to the AS protocol. The significant predictor of adherence in the multivariate model was being diagnosed in a private hospital (v public hospital: adjusted odds ratio [aOR], 1.83; 95% CI, 1.42e2.37; P < 0.001). Significant predictors of nonadherence included being diagnosed by transurethral resection of the prostate (v transrectal ultrasound biopsy [TRUS]: OR, 0.54; 95% CI, 0.39e0.77; P < 0.001) or transperineal biopsy (v TRUS: OR, 0.32; 95% CI, 0.19e0.52; P < 0.001), and being 66 years of age or more at diagnosis (v < 55 years: OR, 0.65; 95% CI, 0.45e0.92; P ¼ 0.015). Conclusion: Almost three-quarters of men who had prostate cancer with low risk of disease progression did not have follow-up investigations consistent with standard AS protocols. The clinical consequences of this shortcoming are unknown.