I do get the problem with a recent(ish) svn, on OS X 10.5.1, python 2.5.1 (from python.org): In [76]: A = array(['a','aa','b']) In [77]: B = array(['d','e']) In [78]: A.searchsorted(B) Out[78]: array([3, 0]) In [79]: numpy.__version__ Out[79]: '1.0.5.dev4722'