  We determine the asymptotics for the variance of the number of zeros of
random linear combinations of orthogonal polynomials of degree $\leq n$ in
subintervals $\left [ a,b\right ] $ of the support of the underlying
orthogonality measure $\mu $. We show that, as $n\rightarrow \infty $, this
variance is asymptotic to $cn$, for some explicit constant $c>0$.
