Introduction: Hypokalemic periodic paralysis (hypoPP) is a rare autosomal dominant skeletal muscle ion channelopathy characterized by recurrent episodes of reversible flaccid paralysis with concurrent hypokalemia. Most of the familial hypoPP patients have missense mutations in the CACNA1S gene, which encodes the α-1S subunit of the L-type voltage-dependent calcium channel. A family with four cases of hypoPP is presented. Material and Methods: A 67-year-old male patient with symptoms of hypokalemic paralysis was examined neurologically and genetically. His family history revealed some cases with some similar symptoms. CACNA1S gene sequencing analysis was performed in the proband and six of his relatives. Results: The missense mutation Arg528His was identified in heterozygosity with the normal allele in the proband, three of his sons, and two other close relatives. Conclusion: The molecular genetic analysis confirmed the diagnosis of hypoPP in several members of the studied family.