Communication difficulties in multicultural clinical settings can be exacerbated by translators, but their actual impact on medical decisions has not been systematically evaluated. This study sought to determine the influence of translators participating in clinical encounters in which English-speaking clinicians offered amniocentesis to Spanish-speaking women by conducting systematic observations of 61 prenatal genetic consultations and recording translators' training and background characteristics and patients' amniocentesis decisions. Translators' behavioral styles were classified according to 10 inductively determined criteria. Translators' approaches were classified as Distant, Authoritative, or Missionary. Whereas the first category remained emotionally detached, the others sought to build rapport and trust with the patient. Quantitative analysis revealed statistically significant associations between translation styles that sought to engender trust and likelihood the pregnant woman agreed to amniocentesis. The authors conclude that translators' affective approaches can influence whether patients accept or decline amniocentesis. (Contains 2 tables and 1 figure.)