We report a case of sciatic nerve entrapment resulting in a patient experiencing pain over the posterior aspect of the knee, simulating a Baker's cyst. Surgical exploration revealed a tight fibrous arch compressing the distal portion of the sciatic nerve, proximal to its bifurcation. Decompression of this entrapment led to complete relief of symptoms. This form of presentation is rare and should be considered as a differential diagnosis when a patient presents with complaints of pain in the back of the knee. Keywords: Sciatic nerve compression, pain in the back of the knee