Objectives: to identify the errors in daily intensive nursing care and analyze them according to the theory of human error. Method: quantitative, descriptive and exploratory study, undertaken at the Intensive Care Center of a hospital in the Brazilian Sentinel Hospital Network. The participants were 36 professionals from the nursing team. The data were collected through semistructured interviews, observation and lexical analysis in the software ALCESTE(r). Results: human error in nursing care can be related to the approach of the system, through active faults and latent conditions. The active faults are represented by the errors in medication administration and not raising the bedside rails. The latent conditions can be related to the communication difficulties in the multiprofessional team, lack of standards and institutional routines and absence of material resources. Conclusion: the errors identified interfere in nursing care and the clients' recovery and can cause damage. Nevertheless, they are treated as common events inherent in daily practice. The need to acknowledge these events is emphasized, stimulating the safety culture at the institution.