  Two sets of archive time series observations of an old open cluster NGC 6791
were re-analysed using an image subtraction technique. We report identification
of four new variables. Proper motion data are available for three of them and
indicate that they are likely cluster members. Photometry of these stars is
discussed along with the data for two earlier identified variables. The sample
analysed includes one yellow and three red stragglers. An eclipsing red
straggler V9 is of particular interest. Cluster membership of this RS Cvn type
binary would imply that its cooler component is in a stage of thermal
inequilibrium. One of variables is a K type red giant showing low-amplitude
variability with a period of about 0.33 d.
