Most examinations of the genetic basis of insecticide resistance have concluded that resistance results from the action of a single or single major gene. Thus, it is commonly believed that insecticide resistance is a single gene (monogenic) trait. However, a review of recent literature on the genetic basis of insecticide resistance revealed that monogenic resistance was usually not supported by the data or statistical analyses. While 79 % of analyses led to the conclusion that resistance was monogenic, data were consistent with a monogenic hypothesis in only 19 % of analyses with a statistical test (monogenic inheritance was formally rejected 81 % of the time). I also comment on three independent examinations of the backcross method (the type of analysis most often used to examine the genetic basis of insecticide resistance) which suggest that backcross analyses should be employed and interpreted cautiously. Primarily, it has been demonstrated that when backcross mortality data are consistent with monogenic inheritance, they are also consistent with one or more polygenic hypotheses. Although backcross data have generally not been consistent with monogenic inheritance, alternative genetic hypothesis were tested in only one study; most backcross data may be consistent only with polygenic inheritance.