Retrieval-induced forgetting (RIF) refers to the finding that the retrieval of an item from memory impairs the retrieval of related items. The extent to which this impairment is found in laboratory tests varies between individuals, and recent studies have reported an association between individual differences in the strength of the RIF effect and other cognitive and clinical factors. The present study investigated the reliability of these individual differences in the RIF effect. A RIF task was administered to the same individuals on two occasions (sessions T1 and T2), one week apart. For Experiments 1 and 2 the final retrieval test at each session made use of a category-cue procedure, whereas Experiment 3 employed category-plus-letter cues, and Experiment 4 used a recognition test. In Experiment 2 the same test items that were studied, practiced, and tested at T1 were also studied, practiced, and tested at T2, but for the remaining three experiments two different item sets were used at T1 and T2. A significant RIF effect was found in all four experiments. A significant correlation was found between RIF scores at T1 and T2 in Experiment 2, but for the other three experiments the correlations between RIF scores at T1 and T2 failed to reach significance. This study therefore failed to find clear evidence for reliable individual differences in RIF performance, except where the same test materials were used for both test sessions. These findings have important implications for studies involving individual differences in RIF performance.