A new ultrafast MR imaging method is proposed and tested, which enables whole-brain fMRI with a true temporal resolution of 1 sec. The method combines a 3D PRESTO pulse sequence with the concept of sensitivity-encoding with multiple receiver coils (SENSE). The so-called PRESTO-SENSE technique is demonstrated on a set of functional block-type motor and visual experiments and compared with conventional functional imaging techniques, such as PRESTO and EPI. Comparable image quality and activation areas are found with all sequences. The noise characteristics of the proposed method are analyzed in detail and their implications for ultrafast fMRI studies are discussed. Magn Reson Med 43:779-786, 2000.