In this work we consider the following N P -hard combinatorial optimization problem from computational biology. Given a set of input strings of equal length, the goal is to identify a maximum cardinality subset of strings that dier maximally in a pre-dened number of positions. First of all we introduce an integer linear programming model for this problem. Second, two variants of a rather simple greedy strategy are proposed. Finally, a large neighborhood search algorithm is presented. A comprehensive experimental comparison among the proposed techniques shows, rst, that larger neighborhood search generally outperforms both greedy strategies. Second, while large neighborhood search shows to be competitive with the stand-alone application of CPLEX for small and medium sized problem instances, it outperforms CPLEX in the context of larger instances.Keywords: Most strings with few bad columns, integer linear programming, large neighborhood search. * A preliminary version of this work appeared at