RR Lyrae stars are astrophysically important class of pulsating variables having many applications in modern astrophysics. Every sixth
known variable star is of this type. According to the fraction of binary systems among various stellar types we should expect to observe
several thousands RR Lyrae stars bound in binaries. However, only one convincing candidate and several less certain candidates are known
today. What is the reason for this interesting bias? It seems that the answer should be sought in the evolutionary stadium characteristics
which bring some special observational constraints. I will discuss the current status of the research in this field and show some
interesting binary candidates.
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