Failed spinal anaesthesia is a critical concern in regional anaesthesia, leading to patient discomfort, increased intraoperative interventions, and potential conversion to general anaesthesia. A failed spinal block may manifest as a total absence of block, inadequate sensory or motor blockade, or insufficient duration. The failure rate varies but is estimated at around 1%–2%, with higher rates reported in obstetric and orthopaedic procedures. Key mechanisms include unsuccessful lumbar puncture, solution injection errors, inadequate intrathecal spread, drug failure, and failure of subsequent management. Anatomical variations, poor patient positioning, and incorrect needling technique contribute to failure. Management strategies depend on the severity of the failure, ranging from postural adjustments and intravenous analgesia to repeating the block or converting to general anaesthesia. Specific cases, such as unilateral, patchy, or inadequate height blocks, require tailored interventions. Repeat spinal injections should be approached cautiously to avoid excessive local anaesthetic doses and total spinal anaesthesia. Postoperative follow-up is essential to document the failure, reassure patients, and assess for underlying spinal pathology in recurrent cases. This article highlights the causes, prevention, and management of failed spinal anaesthesia to improve patient outcomes and anaesthetic practice.