Inclusion Criteria:

1. men and women age 18-65
2. current CB using the clinician-administered Structured Clinical Interview for Compulsive buying (SCI-CB)
3. buying behavior within 2 weeks prior to enrollment

Exclusion Criteria:

1. infrequent buying (i.e. less than one time per week) that does not meet proposed criteria for CB
2. unstable medical illness or clinically significant abnormalities on laboratory tests or physical examination at screen
3. history of seizures
4. myocardial infarction within 6 months
5. current pregnancy or lactation, or inadequate contraception in women of childbearing potential
6. a need for medication other than memantine with possible psychotropic effects or unfavorable interactions;
7. clinically significant suicidality;
8. current Axis I disorder determined by the SCID and SCID-compatible modules for impulse control disorders, except for nicotine dependence
9. lifetime history of bipolar disorder type I or II, dementia, schizophrenia, or any psychotic disorder determined by SCID
10. current or recent (past 3 months) DSM-IV substance abuse or dependence;
11. positive urine drug screen at screening
12. initiation of psychotherapy or behavior therapy within 3 months prior to study baseline
13. previous treatment with memantine
14. treatment with investigational medication or depot neuroleptics within 3 months, with fluoxetine within 6 weeks, or with other psychotropics within 2 weeks prior to study baseline