Instances in which we cannot retrieve information immediately but know that the information might be retrieved later are subjective states that accompany retrieval failure. These are expressed in feeling-of-knowing and Tip-of-the-tongue experiences. In Experiment 1, participants with Parkinson’s disease and older adult controls were given general questions and asked to report when they experienced a TOT state and to give related information about the missing word. The PD group experienced similar levels of TOTs but provided less correct peripheral information related (...) to the target when in a TOT state. In Experiment 2, participants were given a Semantic and an Episodic FOK task. PD patients failed to accurately predict their future memory performance in response to both episodic and semantic cues. Results are interpreted in the context of recent frameworks of memory and metacognition. (shrink)