We aimed to determine the acute physiology and chronic health evaluation (APACHE) II and simplified acute physiology score (SAPS) II in poisoned patients admitted to the poisoning ICU and compare them to see which is a more sensitive and specific system for prognostication of the mortality and complications in these patients. Between February 2013 and July 2013, all patients referring to our centre with any poisoning mandating ICU admission were prospectively included. On ICU arrival, a questionnaire containing the demographic data, parameters of the APACHE II and SAPS II scores, the sum of the scores, complications during the stay and the patients' final outcome (compete recovery versus death) was filled for every single patient. A total of 195 patients were evaluated. Forty-two patients (21.5%) died. Mean SAPS and APACHE scores were 41 AE 16 and 15 AE 6, respectively. Mean SAPS and APACHE scores were significantly different between the survivors and non-survivors. Both scores could successfully prognosticate the development of the complications (p = 0.07 and 0.013, respectively). APACHE II was a better score in prediction of both mortality and later complications in the setting of poisoning ICU. APACHE >22 has a good specificity in determining the mortality and development of further complications in poisoned patients admitted to the medical toxicology ICUs. SAPS II score >59 and >43 can predict the risk of mortality and later complications in these patients, as well.