The Bardet-Biedl syndrome (BBS), a rare autosomal recessive disorder, was first described by Bardet and Biedl in 1920. Here, we are reporting a case of the Bardet-Biedl syndrome with hypokalaemic paralysis. A 22 years old male patient presented with an acute onset, rapidly progressive, flaccid weakness in all four limbs. An examination revealed a moon shaped face, acanthosis nigricans, lower limb polydactyly, central obesity, small testicular size, absence of the axillary and pubic hairs, severely impaired social adaptive functioning and retinitis pigmentosa. The central nervous system examination showed hypotonia, a grade zero power and absent reflexes. The laboratory reports showed that the patient had hypokalaemia and diabetes mellitus. The literature showed hypokalaemic paralysis as a rare complication of the Bardet-Biedl syndrome.