Diagnostic error occurs when a healthcare professional fails to identify a medical condition accurately. This can happen due to misinterpretation of symptoms, inadequate testing, or overlooking critical information. Such errors can lead to incorrect treatments, delayed care, or worsening of the patient's condition. Factors contributing to diagnostic errors include communication breakdowns among healthcare teams, insufficient patient history, and cognitive biases. Improving diagnostic accuracy involves better training, enhanced medical technology, and fostering open communication between patients and providers. Addressing these issues is essential for improving patient safety and outcomes.