BACKGROUND: Most studies of post-traumatic stress disorder following terrorist attacks are of small samples in industrialised nations and take place months or years after the incident. AIMS: To describe reactions following the US embassy bombing in Nairobi and the characteristic features of and risk factors for post-traumatic stress symptoms in a large, non-Western sample soon after the attack. METHOD: A self-report questionnaire which assessed potential risk factors and identified symptoms matching DSM-IV criteria for post-traumatic stress disorder was answered by 2883 Kenyans, 1-3 months after the bombing. RESULTS: Symptoms approximating to the criteria for post-traumatic stress disorder occurred in 35%. Factors associated with post-traumatic stress included female gender, unmarried status, lack of college education, seeing the blast, injury, not recovering from injury, not confiding in a friend, bereavement and financial difficulty since the blast. Many other factors were not significant. CONCLUSIONS: Specific factors often cited to predict marked short-term post-traumatic stress were confirmed in this large, non-Western sample.