The purpose of this study was to examine whether cholinergic treatment of age-associated memory impairment with Linopirdine (DUP 996), a derivate of phenylindoline, affects explicit memory, implicit memory, and primary memory. We also assessed cognitive decision making in a reaction time test. Explicit memory was assessed by face recognition, word recall and a word recognition test, being part of a successive test paradigm. Implicit memory was assessed by primed word fragment completion in the same successive test paradigm. Primary memory was studied by means of digit recall. Thirty-eight elderly subjects fulfilled the criteria for memory impairment. Four groups of subjects were given 10, 20 or 30 mg of DUP 996 or placebo during 4 weeks. A double-blind procedure was applied. No significant treatment effects for recognition memory and priming were obtained in the successive test paradigm. Analysis of dependence/independence between tests did not show any clear pattern of treatment effects. The other explicit memory tests and the reaction time test showed no effect with DUP 996. Because of the range of the different tests used here, the result and the general evidence in other investigations of the cholinergic depletion among aged people, the conclusion is that DUP 996 does not improve memory performance either in explicit, implicit or primary tests.