RationaleNoninvasive blood pressure (BP) monitoring is very important also difficult for accurate diagnosis and monitor of obese patients.AimsThe study aimed to assess the agreement between forearm arm BP and intra‐arterial BP values in a different body and arm positions in obese patients.MethodsThe descriptive study was carried out on 60 intensive care patients with a body mass index above 30 kg/m2 who were monitored with invasive radial BP in the general and surgical intensive care units. BP values obtained from the upper arm and forearm with different arm and body positions were compared with intra‐arterial BP results. Bland‐Altman analysis and correlation coefficient were used for the accuracy of upper and forearm noninvasive BP reading in different positions.ResultsThe best agreement was found between the forearm systolic BP in the supine and half‐sitting position with the arm down and intra‐arterial BP values. Also, the best agreement in diastolic BP was found between the half‐sitting and half‐sitting position with the arm down and intra‐arterial BP.ConclusionsForearm systolic BP measurement, especially in the supine and half‐sitting position with the arm below the heart level position, was best agreement with intra‐arterial measurement, regarded as the gold standard. For this reason, it is more appropriate to use forearm BP measurement in obese patients monitored in intensive care to obtain accurate results.