Abstract Breast cancer, the most common cancer amid women in the majority of countries, is among the most stressful of diseases. The principal effectors of the stress system include the catecholamines epinephrine and norepinephrine. The catecholamines bind to α1-, α2- and β-adrenoceptors (AR). Our group has recently described α2-adrenoceptors in human tumor and non-tumor breast cell lines by reverse transcription (RT)-PCR, immunocytochemistry and binding assays. Moreover, the stimulation by α2-adrenoceptor agonists was associated with increased cell proliferation and tumor growth. On the other hand, we observed a reduction in tumor growth when the animals are treated with the pharmacological α2-antagonist RAUWOLSCINE (RAW). The expression of β2-AR has been described in different experimental models for breast cancer. The aims of the present work were: to assess the effect of β-adrenergic compounds in the human breast cancer cell lines growing in nude mice (IBH-4 and IBH-6); to study the migration potential of these cell lines using video microscopy in three dimensional collagen lattices knowing that migration of tumor cells is a prerequisite for invasion and metastasis development. The daily administration of 1,2mg/kg of the SALBUTAMOL (SALB) significantly diminished tumor growth. The same result was seen when using the α2-antagonist RAW (0,5mg/kg). As an example for tumor IBH-4 treated with SALB, on day 20: 444.16 ± 76.59mm3 vs. 843.40 ± 189.41 mm3, p<0.05; RAW on day 24: 775.04 ± 68.12mm3 vs 1237.84 ± 134.97mm3 p<0.01. Tumor IBH-6, on day 21: SALB: 125.40 ± 25.42mm3 vs. 579.40 ± 207.96mm3 p<0.01. The combined treatment of SALB + RAW did not exert any synergic or additive effect compared with each independent treatment. ERK phosphorylation is in agreement with tumor growth results. When analyzing the migration potential of the cells in response to adrenergic stimulation by three dimension video microscopy in collagen lattices, cell migration was decreased when the cells were treated with RAW, SALB and PROP and increased when treated with epinephrine. The migratory activity for each treatment was calculated as the portion of cells which was locomotory active (% locomoting cells). We conclude that both RAW, acting as α2-AR antagonist and SALB, acting through β-AR, inhibit tumor growth. Regarding cell migration, the results are promising and in agreement with the in vivo experiments. These compounds, devoid of serious side-effects, could eventually be employed to inhibit tumor growth. In the future, it might be useful to analyse the metastatic potential of the cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3266.