The staff required to serve patients influences the quality of the service and is an indicator of positive or adverse events during patient care in hospital settings.Objective: To establish the relationship between the Nurse-patient ratios and nurse assistants patient ratios and the probability of occurrence of adverse events during a shift of three intensive care units in Ibague, Colombia.Methods: An ecological study, longitudinal, three intensive care units in 1656 Ibague-Colombia shifts observed.Results: There was an association between the Nurse-patient ratios and the probability of mortality incidence 1/5. (OR: 1.1) 95%, unemployment cardiorrespiratorio.1 / 5 (OR 1.38) 95% infections resulting from health care fifth (OR: 1.10) 95%. The first two variables were studied as general because the limitation imposed by the underreporting demonstrated during the study period. It was shown that only variable, of those analyzed in the study, significantly related to the ratio of nurse assistants-patient ratio the incidence of pressure sores fourth (OR: 1.272) CI: 95%Conclusions: The Nurse-patient ratio and nurse assistants-patient ratio adverse events are associated with no statistical significance, it is necessary to increase the number of observations and studies to draw strong conclusions about the number of patients per nurse decreasing the risk of AD.