OBJECTIVES: The objective of this study was to examine urinary, rectal, erectile side effects, and cancer specific survival in localized prostate cancer patients who were treated with immediate treatment or conservative management. METHODS: Using the Surveillance Epidemiology and End Results-Medicare linked database, 6,868 patients ≥ 66 years of age diagnosed with localized low risk prostate cancer in the year 2004 and 2005 were identified. Patients who received either immediate treatment or delayed treatment (> 6 months after diagnosis) were followed for a period of 5 years to determine toxicities and survival. Propensity score matching was used to adjust for selection bias associated with treatment type received. The presence of toxicity in each cohort was determined using logistic regression. The Cox proportional hazard model was used to estimate prostate cancer specific survival rates. RESULTS: Overall, 735 patients received delayed treatment and 6,133 patients received immediate treatment. Multivariate logistic regression analysis showed that the conservative management group was found to have lower odds for urinary complications (odds ratio: 0.824, p value<0.0001), rectal complications (odds ratio: 0.770, p value<0.0001) and erectile toxicities (odds ratio: 0.636, p value < 0.0001) compared to the immediate treatment group within 5 years of diagnosis. The results of survival analysis showed that there was no additional hazard of dying due to prostate cancer in conservative management within a 5 year time period among studied patients than those in the immediate treatment group (Hazard ratio: 0.736, p value: 0.2696). CONCLUSIONS: Patients ≥ 66 years of age diagnosed with low risk prostate cancer are not at additional risk of dying due to prostate cancer within a 5 year time period if kept on conservative management. The results of this study should be interpreted with caution because we could not differentiate active surveillance from watchful waiting group from the database.