OBJECTIVE Paracetamol overdose belongs to frequent calls to Toxicological Information Centre (TIC) in the Czech Republic and to the National Toxicological Information Centre (NTIC) in Slovakia. The aim of the study was to evaluate outcomes and side effects of paracetamol overdose in both countries. METHODS Data concerning paracetamol poisoning extracted from TIC and NTIC databases 2000-2013 and discharge reports were analysed. Numbers and outcomes in patients presenting within 24 hours of a single paracetamol overdose were compared in relation to 3 paracetamol concentration bands (≤ 100 mg/l, 100-149 mg/l, and 150 mg/l). RESULTS 5397 inquiries concerning paracetamol were recorded in TIS and NTIC. Data from 196 discharge reports with plasma level were studied. Median age of the patients was 18 (0.2-86) years. Eight/196 (4.1%) patients developed side effects after N-acetylcysteine (NAC) administration. 120 cases fulfilled time criteria of the study and were divided into 3 groups, where 55.7%, 73.1% and 96.9% patients have been treated with NAC. Among these 120 patients, favourable outcome was seen in 100%, 100%, and 92.8%, respectively. One death due to suicidal attempt with plasma level 407 mg/l presenting at 20 hours has been recorded among 120 patients. No patient without NAC treatment died due to acute overdose and plasma concentration ≤ 150 mg/I at 4 hours. CONCLUSIONS These data support the opinion that NAC should not be used in patients with < 149 mg/l levels in absence of higher risk factors because of very low risk of hepatotoxicity on one side, and side effects on the other side.