Dialysis hypotension is one of the most prevalence symptoms of dialysis and occurs in 40% of treatment sessions. Detection and prediction of hypotension is important for the well-being of the patient and for optimizing treatment. The aim of this study was to construct optical system to monitor blood pressure (BP) continuously and without cuff in hemodialysis based on pulse transit time (PTT) method. To measure the BP changes, dual-channel optical system were developed. In this study, individuals were classified into two groups of normal and hemodialysis. In both groups, BP and consequently PTT were earned three times in different positions. After the initial calibration, the regression equation was drawn for each subject. In normal group, each subject was placed in the supine position and BP was measured both by designed system and sphyg-momanometer cuff. During BP measurements, in addition to BP, blood pressure decline was also monitored by optical system. For hemodialysis group, the same measurement setup was adopted. In both groups, the error between cuff method and PTT was calculated. Correlation coefficients for BPcuff vs BPPTT were calculated and Bland–Altman plot was performed for the normal and hemodialysis groups. In this study 16 subjects participated. The results for normal group showed that maximum difference between cuff method and the present method was 14 mmHg and for dialysis group was 16 mmHg. Bland–Altman plot in normal group revealed limits of agreement from 13.98 to 13.18 mmHg. Considering hemodialysis group, limits of agreement were from -15.94 to 13.88 mmHg. The correlation coefficient was 0.74 for normal group and was 0.72 for hemodialysis group. The proposed system can monitor BP continuously and diagnose sudden hypotension. So it can be recommended as a useful method to indicate hypotension and can be used for dialysis unit.