Acetylcholinesterase (AChE), arylesterase (AE), carboxylesterase (CE), and cholinesterase (ChE) activities were determined in six adult populations of the lesser grain borer, Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae) collected from grain warehouses in various areas of Punjab, namely Lahore (L), Sialkot (S), Wazirabad (W), Multan (M), Chkhawatni (C), and Karachi (K). The multiple forms of esterases were resolved by polyacrylamide gel electrophoresis (PAGE) and activities determined biochemically, using a spectrophotometer. All the strains had the same AChE activity except Sialkot strain, which had 46% more activity than the susceptible K strain. Similarly K, S, W, L, and C strains exhibited almost the same AE level, whereas the M strain showed 29% lower activity than K strain. The CE activity of L (352%), S (198%) and C (214%) strains and ChE activity of L (178%) and C (317%) strains were significantly higher than that of K strain. The total esterases of L, S and C strains showed respectively 152%, 63% and 73% higher activity than the susceptible K strain. The PAGE pattern of various esterases coincided with the biochemical analysis. The variable thickness of the bands in the gel indicated relative esterase induction that could be correlated with the development of resistance in R. dominica.