Aim: The primary aim of this study is to evaluate patients who present to the emergency department with atypical symptoms in terms of occult Carbon monoxide (CO) poisoning, and the secondary aim is to compare the invasive and non-invasive values of Carboxyhemglobin (COHb) levels in patients with high CO levels. Material and Method: This prospective and descriptive study was conducted on 2775 adult patients who visited the Emergency Department (ED) between January 1 and March 31, 2015. The COHb levels of the individuals who applied to the emergency department with non-specific complaints were measured with a non-invasive multiwave pulse oximeter device and the date of application, age, gender, complaint, smoking history, pregnancy status, pulse COHb, blood COHb and blood metHb parameters were recorded in the preformed form. Values under 10% in smokers and under 6.6% in non-smokers were recorded as secret COHb intoxication. Results: 52.8% of the patients were male and 34.4% were smokers. The rate of pregnant women among female patients was 13.4%. The first three complaints were shortness of breath, chest pain and stomach ache. It was determined that the mean COHb of the patients was 1.44±1.65 in arterial blood gas and 1.75±1.63 in finger measurement. A highly significant positive correlation was found between the two averages. The COHb value measured by both techniques was higher in male patients and in smokers and non-pregnant patients. The rate of latent COHb intoxication was determined as 1% in smokers and 0.1% in non-smokers. Conclusion: We came to the conclusion that non-invasive COHb measurement can make positive contributions to the diagnosis of secret carbonmonoxyde intoxications.