Enzymes are powerful biocatalysts without which the majority of chemical reactions in the biological system would not occur. One of the most effective enzymes in nature, acetylcholinesterase (AChE) belongs to the enzyme group of hydrolases. The physiological role of AChE is to hydrolyse the neurotransmitter acetylcholine (ACh) after transmission of a nervous pulse to acetate and choline and thus reduce its activity. It is an important factor in the treatment of severe neurodegenerative diseases such as Alzheimer's disease. Alzheimer's Disease (AD) is the most common type of dementia in the modern world. AD is an incurable disease of nerve cells (neurons) and surrounding structures with a deadly outcome. Cholinesterase inhibitors, along with the other studied methods, are used to alleviate the symptoms of this progressive disease, and the ultimate goal is to find a cure. The aim of the study was to investigate the inhibitory effect of selected organic sulfides (inhibitors) on the enzyme acetylcholinesterase using Ellman’s method. Ellman's method is based on the reaction of Ellman's reagent and the thiol groups yielding a yellow coloured complex. Between the selected sulfides dimethyl trisulfide showed the highest inhibition capability of 40.23% at a concentration of 568 μM. Reduction of the concentration of the inhibitor decreased the inhibitory effect. Dipropyl trisulfide was the only sulfide that did not show any inhibitory activity at tested concentrations.