The biostratigraphic distribution and qualitative relative abundance of Quaternary-Pliocene diatoms from Ocean Drilling Program Leg 188, Sites 1165 (64.380 degrees S, 67.219 degrees E) and 1166 (67.696 degrees S, 74.787 degrees E) offshore from East Antarctica, are documented in this report. The upper approximately 50 meters below seafloor (mbsf) of Hole 1165B consists of brown diatom-bearing silty clay spanning the upper Pleistocene to lower Pliocene. The diatom stratigraphy indicates a disconformity at approximately 17.1 mbsf of 0.5- to 0.6-m.y. duration. The integration of biostratigraphic and magnetostratigraphic data identified other disconformities at approximately 6.0, 14.4, 15.6, and 16.0 mbsf, but the duration of these hiatuses cannot be resolved through diatom biostratigraphy. In Hole 1166A, a narrow interval of diatomaceous Quaternary sediment is identified in the upper 2.92 mbsf and dated biostratigraphically at <0.38 Ma. The remaining Quaternary-Pliocene section is dominated by diamicton, except at approximately 114 mbsf, where two thin diatomaceous beds are present. The lower bed is approximately 65 cm thick, 2.5-2.7 to 2.7-3.2 Ma in age, and possibly disconformably overlain by the upper bed, which is approximately 15 cm thick and 1.8-2.0 to 2.1-2.5 Ma in age. The Pliocene assemblages in Hole 1166A contain components of both Southern Ocean and Antarctic continental shelf (Ross Sea) diatom floras.