This report investigated the origin of H(2)S in a newborn boy with sulfhaemoglobin induced cyanosis, who died because of multiple organ failure. Frozen material was collected and studied after death. The results suggest that enzymes had been released from deteriorating organs into the blood and abdominal fluid, and that the reaction of one of these enzymes with sulfur containing amino acids might have resulted in increased H(2)S concentrations. It is hypothesised that this release of enzymes resulted from a haemolysin produced by an invasive haemolytic Escherichia coli that was found in the blood and organs of this patient.