Gelatin sponge (Gelfoam) is quite often used for haemostasis during spine surgery. However due to its property of osmotic expansion after coming in contact with blood, it has the potential to cause serious complications as a result of compression of nearby vital neurological tissues. We report a case of cauda equina syndrome due to retained Gelfoam during spinal surgery. A 35 year old female patient presented with complaints of pain and numbness in lower limbs for 5 months. MRI was suggestive of disc herniation at L4/L5. Lumbar discectomy was done and gelfoam was used for haemostasis. However, patient developed post-operative neurological complications suggestive of cauda equina syndrome. MRI showed gelfoam induced compression of dural sac. Gelfoam removal was done after which marked improvement in symptoms was observed. Conclusion: Hemostatic agents like Gelfoam which are often used during surgeries have the potential to cause compression of vital structures. Therefore, these should be removed once haemostatic control is accomplished and if it is to be retained, prompt post operatively monitoring is essential.