In this work we study the size of Boyer-Moore automata introduced in Knuth, Morris & Pratt's famous paper on pattern matching. We experimentally show that a finite class of binary patterns produce very large Boyer-Moore automata, and find one particular case which we conjecture, generates automata of size Omega(m(6)). Further experimental results suggest that the maximal size could be a polynomial of O(m(7)), or even an exponential O(2(0.4m)), where m is the length of the pattern. (C) 2009 Elsevier B.V. All rights reserved.