In order to extend the applications of OR-PAM to clinical applications, ease of use and real-time operation will be key factors to be implemented. Both laser pulse repetition rate (PRR) and scanning speed are important factors affecting the imaging speed. Recently, Hu et al.10 developed a second-generation OR-PAM system based on mechanical translation of an imaging head. They reported a 70-min image acquisition time for a FOV with a pixel size of . Translating the imaging head instead of the living object accelerated the scanning speed by a factor of five.10 However, despite high image quality, imaging speed was far below real-time rates. Xie et al.11 reported a laser-scanning OR-PAM with only laser light being raster scanned by an galvanometer mirror system while keeping the ultrasonic transducer stationary. The system enabled fast scanning speed but with imaging speed limited mainly by their kHz PRR laser. In 2010, our group demonstrated laser-scanning OR-PAM imaging using passively Q-switched microchip lasers with PRR exceeding 10 kHz and fiber lasers with 100 kHz PRR.12 Later, a 50 kHz fiber-laser operating at 1064 nm for OR-PAM is reported by Wang et al.13 In 2011, our group demonstrated an OR-PAM system using a fiber laser source with high repetition rate of up to 600 kHz capable of C-scan imaging at four frames per second.14 However, the system was limited to acquisition of only two to three volumetric datasets due to memory limitations, and sustained real-time imaging was not possible. Rao et al.15 reported a high-speed OR-PAM system in an inverted microscope configuration with Au nanoparticle-assisted sub-diffraction-limit resolution. With a 100 kHz pulsed laser, a stationary ultrasonic transducer and a two-dimensional (2-D)-Galvo system scanning the collimated laser beam through the pupil of objective lens, their system demonstrated its ability to achieve in vivo imaging of microcirculation in mouse skin at 18 three-dimensional volumes per second with repeated 2-D raster scans of 100 by 50 points for image size with 0.23 μm point size and 256 A-line measurements at each points. However, their setup worked only in transmission mode, which limits its applications for thick soft tissue. Also, imaging microcirculation in their system required the assistance of nanoparticle agents. In 16, a second generation OR-PAM system was used to acquire ECG-gated measurements of blood pulse-waves in small vessels. This novel approach offered outstanding image quality and provided for the first time estimates of pulse-wave velocities using photoacoustic imaging; however, real-time C-scan visualization was not possible. Yao et al.17 demonstrated an immersible MEMS-mirror scanning system capable of high volumetric frame rates and imaging of carbon particles and red blood cells; however, they did not correlate microvascular hemodynamics with cardiac pulsations, which could be important in pulse-wave velocity studies. In our previous studies,14 we were not able to image dynamic processes due to previous data acquisition limitations of our system. In this paper, we demonstrate an improved fast C-scan OR-PAM system, which enables both sustained imaging and real-time imaging. We report in vivo label-free reflection-mode real-time OR-PAM imaging of micro-hemodynamics correlated with cardiac pulsations and anticipate this system can play an important role in future functional imaging studies of neuronal-hemodynamic coupling.