The aim of this paper is to investigate the effect of unbalanced moment on the capacity of high strength concrete slab-column connections. The main objectives of this research were to investigate the effect of concrete compressive strength, in addition to the effect of changing the slab reinforcement ratio specimens on the slab-column connection capacity. This paper comprises experimental and analytical studies to investigate the behavior of slab-column connections by testing six RC slab-column connections. The experimental connection capacities were compared to the analytical ones obtained from ACI, BS and ECP equations. Modes of failure, predicted ultimate capacity of slab-column connections for different slab reinforcement ratios (µ) and different concrete compressive strength (fcu) and the applicability of the design equations given in the investigated codes for the design of HSC connections are introduced. This study comprises experimental and analytical studies to investigate the behavior of slab-column connection to transfer moment by testing six slabs. Based on the results of the experimental and the adopted analytical models, it is possible to predict the applicability of the equations given in ECP-2667 [2] for the determination of the HSC slab- column connection capacity. This research includes two phases; experimental, and analytical. Each phase of this study is discussed briefly in the following subsections.