Recognition memory was studied in young and elderly women by assessing memory strength and response bias using Signal Detection Theory methodology. Young women (mean age 21 years; n = 8) had better recognition memory (d' and d'e) than did elderly women (mean age 71 years; n = 16) but the groups did not differ significantly on correct recognitions (hit rate) or incorrect recognitions (false affirmative rate). Evaluation of response bias indicated that the elderly women adopted a lax response strategy which resulted in an inflated correct recognition rate. The data indicate that, in aging research, evaluation of memory in terms of correct and incorrect recognitions can lead to erroneous interpretations, due to uncontrolled bias effects. Age does adversely influence recognition memory strength suggesting that acquisition and/or storage processes are not invariant with age.