Statistical summaries of streamflow records through 2007 for gaging stations in Oklahoma and parts of adjacent states are presented for 238 stations with at least 10 years of streamflow record. Streamflow at 120 of the stations is regulated for specific periods. Data for these periods were analyzed separately to account for changes in streamflow because of regulation by dams or other human modification of streamflow. A brief description of the location, drainage area, and period of record is given for each gaging station. A brief regulation history also is given for stations with a regulated streamflow record. This descriptive information is followed by tables of mean and median monthly and annual discharges, magnitude and probability of exceedance of annual instantaneous peak flows, durations of daily mean flow, magnitude and probability of nonexceedance of annual low flows, and magnitude and probability of nonexceedance of seasonal low flows.