This study investigated treatment patterns among Louisiana residents diagnosed with clinically localized prostate cancer in 2001 and factors that may be associated with the treatment. The differences in the initial treatment between 1997 and 2001 were also examined. The data were collected from hospital medical records, supplemented by information from freestanding radiation centers and physicians' offices. We assessed the associations of initial treatment with demographic factors such as age, race, health insurance status, type of healthcare facility, area of residence, county poverty, and clinical factors such as Gleason score, PSA, and comorbidity in univariate and logistic multivariate regression analyses. Our study found that patients clinically diagnosed with localized prostate cancer in 2001 received the following treatments: radical prostatectomy (41.4%), radiation (29.7%), hormone (16.2%), or watchful waiting (11.9%). White patients, older patients, patients with private insurance and patients diagnosed or treated in hospitals were more likely (p < 0.05) to receive aggressive therapy (i.e., radical prostatectomy or radiation) than others after controlling for the demographic and clinical factors. Poverty level and comorbidity were inversely associated with receiving aggressive therapy in univariate analysis. But after adjusting for other factors, these associations were no longer statistically significant. Patients with elevated PSA and high Gleason scores were less likely to receive radical prostatectomy even after the adjustment. From 1997 to 2001, utilization of radiation and hormonal therapies increased, and watchful waiting decreased among newly diagnosed prostate cancer patients. Utilization of radical prostatectomy showed no significant change over time.