Initial histologic sections of specimens from colorectal biopsies of putative lesions may lack polyps. These sections may contain lymphoid aggregates that seemingly correlate with endoscopic findings; however; additional sections might contain polyps. We reviewed 83 specimens from colorectal biopsies of putative lesions for which initial sections lacked polyps. Our objectives were to determine the incidence of polyps within additional sections and to determine whether the presence of lymphoid aggregates within initial sections excludes the presence of polyps within additional sections. Eight specimens (10%) contained polyps (5 adenomatous, 3 hyperplastic), which remained histologically occult until examination to depths of approximately 120 to 380 microm. Five polyps (62%) were associated with lymphoid aggregates that were present within initial sections. We conclude that additional sections may contain surprisingly large numbers of polyps and that lymphoid aggregates present within initial sections fail to exclude the presence of polyps within additional sections.