Although intraductal carcinoma of the prostate (IDC-P) is typically present on biopsies in which there is also invasive prostate carcinoma of Gleason pattern 4 or 5 and an associated unfavorable outcome, there are limited studies on IDC-P in needle core biopsies or transurethral resections (TURP) with only a concomitant low-grade invasive component. There are differing opinions on incorporating IDC-P into the Gleason score in such cases. The aim of this study was to investigate clinical outcomes and radical prostatectomy (RP) findings in patients with Gleason 3+3=6 and IDC-P on biopsy or TURP. We identified 73 patients in our consult files (2001 to 2014) who had IDC-P and Gleason score 6 carcinoma on biopsy or TURP with no invasive higher Gleason grade component. Clinical follow-up information was available in 62 patients. Treatment was RP in 14 patients, radiation therapy in 31 patients, androgen deprivation therapy in 1 patient, and cryotherapy in 1 patient. Four patients were found to have metastatic disease at the time of diagnosis and were treated with chemotherapy. Eleven patients underwent active surveillance after diagnosis, of which 6 were eventually treated for progressive disease. The 14 RP specimens were centrally reviewed, and 86% had extensive IDC-P present. The Gleason grades in these 14 RP cases were 3+3=6 in 21%, 3+4=7 in 36%, 4+3=7 in 29%, and 4+4=8 in 14%. Pathologic stage was pT2 in 36%, pT3a in 36%, and pT3b in 28%. After 3 years, there was a 20% actuarial rate of disease progression in men who underwent either RP or radiation therapy. In summary, most men with IDC-P on biopsy/TURP have aggressive tumors, even when the invasive tumor on biopsy is Gleason score 6. As a minority of men may only have Gleason 6 invasive cancer at RP and a favorable prognosis, we recommend that IDC-P on biopsy/TURP be reported separately and not assigned a Gleason score.