This study was carried out to investigate the neurotoxic and immunotoxic effects of trichloroacetic acid (TCA) on rats at subchronic exposure. The neurotoxic effects of TCA were evaluated by measuring the activities of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Biomarkers selected for immunotoxic monitoring were the activities of adenosine deaminase (ADA) and myeloperoxidase (MPO) in various tissues of rats exposed to 2000 parts per million (ppm) dosage of TCA for 52 days. Results showed that the administrations of TCA decreased BChE activities in heart and lungs tissue of the rats treated with TCA. With regard to the immunotoxic effects, ADA activity significantly decreased in the heart, lungs and spleen whereas MPO activity increased after subchronic exposure with 2000 ppm dosage in all of the tissues except for heart tissue of rats compared with controls. The observations presented led us to conclude that the administration of TCA at subchronic was decreased BChE and ADA activities whereas increased MPO activity in various tissues of rats. This may reflect the potential role of these parameters as useful biomarkers for toxicity of TCA.