The spectroscopy of hydrogen iodide Rydberg states is investigated by resonantly enhanced multiphoton ionization (REMPI), utilizing time-of-flight mass spectrometry for detection. A (2+1) REMPI excitation mechanism provides access to electronic states in the region 64 641-71 352 cm(-1). Two-photon selection rules allow the observation of transitions forbidden in the HI absorption experiments. Many of the assigned Rydberg states contain underlying, unassigned structure with anomalous intensity fluctuations and apparent breaking off of branches. Additionally, we observe autoionized levels, most likely accessed by either a (3+1) or a direct four-photon excitation. Molecular constants are calculated for all HI bands observed. Also included is the first REMPI study of iodine atoms coming from photolyzed HI precursor.