OBJETIVO: Identificar los factores sociodemográficos, de salud y apoyo social relacionados con las lesiones accidentales en adultos mayores residentes de colonias urbanas marginales de las ciudades de Cuernavaca, Chilpancingo, Guadalajara y Culiacán. MATERIAL Y MÉTODOS: En 2004-2005 se llevó a cabo un estudio transversal; mediante muestra no probabilística, se entrevistó a 799 adultos mayores; se emplearon pruebas no paramétricas y un modelo multivariado de regresión logística. RESULTADOS: Del total de entrevistas, 37% notificaron lesiones y la causa principal fueron las caídas (54%). El hogar fue el sitio con mayor número de accidentes (52%). Los factores de riesgo asociados fueron edad avanzada, trabajar, mayor número de enfermedades, mayor consumo de medicamentos, remedios y bebidas alcohólicas, percepción de "mala salud", apoyo familiar inadecuado y ser cuidador de otros. CONCLUSIONES: La multicausalidad obliga, por una parte, a que toda la sociedad participe y, por la otra, a la intervención del área de la salud para prevenir y atender el problema.OBJECTIVE: To identify factors (sociodemographic, health, and social support) associated with the presence of accidental injuries in older adults living in deprived urban neighborhoods in four Mexican municipalities. MATERIAL AND METHODS: Cross-sectional survey carried out in 2004-2005, with a non-probabilistic, intentional sample of 799 male and female elderly living in deprived urban areas in four Mexican municipalities. For the statistical analysis, non-parametric tests and multivariate logistic regression models were used. RESULTS: More than a third (37%) of the sample reported injuries; with falls being the main cause. Home was the venue where most accidents took place (52%). Risk factors for accidental injuries were: advanced age, working, greater number of illnesses, consumption of more medicines and remedies, self-perception of "poor" health , consumption of alcoholic beverages, inadequate family support and being a caretaker of others. CONCLUSIONS: The multi-causality of accidental injuries in older adults demands the participation of all sectors of society, and particularly public health interventions.