A couple showing signs of cholinergic crisis was admitted to the hospital. Analyses with high-performance liquid chromatography and gas chromatography-mass spectrometry conducted on serum, urine, and stomach contents that were collected few hours after first symptoms showed the presence of aldicarb, which is the most potent carbamate insecticide on the market. A murder attempt was suspected because the patients showed the first signs some minutes after drinking coffee upon returning home and no commercial products containing aldicarb were found in the house. Because of the reversibility of inhibition of acetylcholinesterase, the patients recovered after treatment with atropine and toxogonin. They left the hospital after 12 days. To our knowledge, the serum concentrations of aldicarb reported in this paper are the highest reported for a nonfatal case.