Intrathoracic petechiae (IP), the most common gross finding in sudden infant death syndrome (SIDS) cases at autopsy, suggest upper airway obstruction (UAO) occurs during the terminal event. If true, IP would be expected more frequently among SIDS cases found face down compared to other face positions. We compare the rates of IP in SIDS cases found face down versus other face positions. A retrospective 15-year review of IP among all cases of SIDS occurring from 1991 through 2005 accessioned by the San Diego County Medical Examiner's Office was conducted. The presence or absence of IP was based on both gross and microscopic observations of the thoracic organs. The severity of thymic petechiae was scored semiquantitatively from microscopic observations. There were 489 SIDS cases during the study period. Sixteen of these were excluded because their deaths had been delayed by initially successful cardiopulmonary resuscitation. Among the remaining 473 SIDS cases, face position when found was specifically described for 332 (70%). Of 122 cases found face down, 112 (92%) had IP, compared to 85% (179) of 210 infants found with the face up or to the side (P = 0.06). The groups were not different with respect to age or gender, but the racial distribution was significantly different (P = 0.004). African-American infants comprised 28% of the found face down group compared to only 12% of the face up or side group. Our data do not support a role for external UAO caused by face positioning directly into the sleep surface in SIDS, but are consistent with internal UAO associated with apnea or gasping before dying of SIDS.