There is a perception that tamoxifen causes weightgain in breast cancer patients. The purpose ofthis research study was to determine if weightgain is associated with tamoxifen therapy and toobserve the impact of weight gain on recurrenceand survival. Prognostic indicators, changes in weight, anddisease status from diagnosis to the end oftreatment were studied in 200 consecutive Stage Iand II breast cancer patients, not receiving systemicchemotherapy, admitted from 1986 to the present, withobservation periods ranging from 3–5 years. A meanweight gain of 1.2 Kgs was seen inall patients; however, weight gain was not significantlydifferent for those receiving tamoxifen vs. those notreceiving tamoxifen, (P=0.66, CI 95% forthe difference –1.8 Kgs to +1.2 Kgs). Weightgain during treatment with tamoxifen was not correlatedwith treatment duration or with recurrence or survival.Age at diagnosis was positively correlated to weightgain in all groups. Our data failed toshow that tamoxifen is associated with weight gain.The moderate weight gain observed in this patientpopulation is comparable to the general aging disease-freepopulation and may not be treatment-related. These findingsmay help to alleviate some concerns of bothphysicians and patients when tamoxifen is the drugof choice for adjuvant therapy.