The dependence of mass ration of eclipsing binary system on period has been studied. It has been found that semi-detached systems obey the relation m₂/m₁ = 0.64 - 0.079P or m₂/m₁ = 0.29 - 0.028P depending upon whether the mass ratio is >0.3 or <0.3. The mass ratio of detached systems generally appears to be independent of the period.
