This is a case report of 25-year old, unemployed male, admitted to hospital due to acute onset of the left foot drop, subsequent walking difficulty and numbness of the left calf and foot. Symptoms began after prolonged sleep with previous heroin abuse by sniffing. During neurological examination, mild weakness of knee flexors, moderate weakness of plantar flexors and paralysis of foot dorsiflexors, together with hypesthesia of the left calf, foot and fingers, predominantly in the innervation area of common peroneal nerve on the same side, were observed. The electrophysiologic examination revealed predominant involvement of peroneal division within the sciatic nerve, together with recorded conduction block indicating the compression as possible mechanism of nerve injury. The patient was administered corticosteroid therapy during two months, what resulted in almost complete recovery. The peculiarity of this case report is in the presence of the sciatic nerve "Saturday night palsy" with possible effect of former heroin abuse.