Objectives: Tumor cell insensitivity to anticancer drugs frequently appears as multi-drug resistance(MDR). MDR is associated with over-expression of one or more of a set of at least 10 different molecules, causing reduced drug levels at the intracellular target site, by removing these drugs from cells. Clinically, MDR is one of the major causes for chemotherapeutic treatment failure in cancer patients. Methods: Patients in this study were healthy women and women with varying stages of breast carcinoma defined by the TNM system (AJCCSERR). Stimulated whole saliva (SWS) was analyzed using SDS-gel electrophoresis, Western blot using MDR1 and BCRP antibodies, and computer densitometry analyses. Data were analyzed using the Student's t test and Spearman's correlations. Results: Preliminary data revealed, MDR1 and breast cancer resistance protein (BCRP) in breast cancer subject SWS samples at lower levels than normal control samples. Breast cancer patient samples that were treated differently (i.e., chemotherapy, radiation, surgery, etc.), and post-therapy SWS samples showed different antibody levels dependent on the treatment outcome (P<0.05). Patients that were in remission and doing well showed significantly higher levels of the MDR1 and BCRP antibodies when compared to patients that had recurrence of cancer or that died (P<0.05). Salivary MDR1 and BCRP levels were highly correlated (r=0.55, P<0.05). Conclusions: Identification of the recognized MDR proteins may prove helpful when diagnosing, choosing a chemical substrate for cancer therapeutics, and monitoring post-therapeutic outcomes.