The prime goal of this paper is to offer an overview of main scientific points in epidemiology, genetics, pathogenesis, clinical course and therapeutic strategies in stiff person syndrome (SPS). This syndrome is characterized by progressive muscle rigidity and painful muscle spasms. Three major forms of SPS are described, according to the pathophysiologic basis, autoimmune, paraneoplastic and idiopathic SPS. In autoimmune form of SPS the antibodies are specific for an enzyme (glutamic acid decarboxylase, GAD). If the paraneoplastic form takes place, the antibodies may be specific for presynaptic (amphyphysin) or the postsynaptic protein (gephyrin). The SPS diagnosis should be based on clinical, laboratory and electromyoneurographic criteria, according to Gordon and Lorish. The therapeutic approaches are focused on symptomatic therapy managing the muscle spasm and on possible immunomodulatory procedures to attenuate an autoimmune reaction. Two cases of SPS are reported in the Republic Croatia since 2005. Although it is a rare medical condition, SPS is of clinical importance, especially because it may be the first sign of an underlying undiagnosed malignant disease or if the anesthesia is necessary in SPS patient.