Asymmetrical hydraulic fractures have been observed in the field to reduce the efficiency of such stimulation treatments. Efforts have been made to investigate asymmetrical hydraulic fractures by imaging their initiation using microseismic imaging technology developed in-house. Images of the fracture initiation were generated using the located sources of microseismic events. Analyses of these images indicate that the initiation of an asymmetrical hydraulic fracture is a complex process. While asymmetrical fractures were generated under asymmetrical stress fields along the length direction, selective propagation along the height direction was also observed, as well as nonalignment and reorientation of the fractures near the borehole. Scarce distribution of microseismic events near the borehole may indicate poor connection between the far-field fracture and the borehole. Dense distribution of microseismic events near the borehole probably results from the coupled effect of fluid leakoff and stress-induced tensile fracturing.