'Insignificant' prostate cancer is defined as disease of virulence insufficient to threaten survival. In this review, which describes nine articles and two abstracts discussing almost 800 cases, we discuss the correlation of such 'insignificant' biopsy findings in the context of subsequent radical prostatectomy data. From our review, minimal disease on biopsy does not reliably predict minimal disease in the subsequent prostatectomy specimen, in terms of the size and grade of tumor, extracapsular extension or positive margins. Thus, reasoned accounting should be made of other data before undertaking a course of radiation therapy as monotherapy, particularly prostate-specific antigen kinetics and potential molecular markers.