We show that Nechiporuk's method [I. Wegener, The Complexity of Boolean Fun
ctions, Teubner-Wiley, New York, 1987] for proving lower bounds for Boolean
formulas can be extended to the quantum case. This leads to an Omega (n(2)
/log(2)n) lower bound for quantum formulas computing an explicit function.
The only known previous explicit lower bound for quantum formulas [A. Yao,
Proceedings of 34th IEEE Symposium on Foundations of Computer Science, IEEE
Computer Society Press, Los Alamitos, CA, 1993, pp. 352-361] states that t
he majority function does not have a linear-size quantum formula. We also s
how that quantum formulas can be simulated by Boolean circuits of almost th
e same size.