"Primary ciliary dyskinesia" is a group of various genetic diseases. A common property is various axonemal defects leading to ciliary dysfunction, which causes the typical clinical picture. Situs inversus occurs as a facultative symptom in half the cases. This combination is known as "Kartagener's syndrome", thus being a characteristic combination of symptoms, but no nosologic entity. Autosomal recessive inheritance has been proven in primary ciliary dyskinesia, but dominant new mutations can not as yet be excluded for sporadic cases.