Rock mass encountered in the field is usually discontinuous and jointed, with fractures ranging from micro-cracks to large-scale jointing. Due to excavation and subsequent stress redistribution, existing cracks might widen and several new cracks might form. The crack growth characteristics in rock, mainly their initiation, propagation and coalescence, become of utmost importance. Many researchers have widely studied this by testing actual and simulated rock samples with pre-existing flaws under different loading environments. Extensive literature is available on the crack growth characteristics under static or quasi-static loading, but there is little understanding of their behaviour under sustained or creep loading. However, it has also been observed that fractures can propagate along with creep deformation when stress concentration is close to its critical strength. This type of slow crack growth is called subcritical crack growth and is often observed in brittle rocks under specific environmental conditions such as saturation and humidity. This paper presents some of the initial test results of saturated artificially prepared rock samples using gypsum with pre-existing narrow flaws of different angles under uniaxial sustained loading. It is observed that, for all angles, slow tensile crack growth is observed, followed by sudden failure due to instantaneous shear crack. A higher orientation angle of a flaw has a more significant deterrent effect than a lower flaw angle. The different types of crack observed are pointed out along with the situation it arises. Time to failure decreases with increased flaw angle, and multiple tensile cracks are observed. This study should be helpful for a better understanding of the long-term performance of many rock engineering applications where fracture growth becomes important.