Turning is an important activity of daily living and often compromised post-stroke. The fall rate for post-stroke individuals while turning is nearly four times as high compared to healthy adults, with most falls resulting in injury. Thus, there is a need for evidencebased rehabilitation targets to improve turning performance for post-stroke individuals. To produce well-coordinated movements, muscles can be organized into muscle modules (i.e., groups of co-excited muscles). Post-stroke these modules can be merged, leading to impaired muscle coordination and walking performance. However, the relationship between impaired coordination and turning performance is not well understood. Thus, the purpose of this study was to analyze the influence of impaired muscle coordination (i.e., merged modules) on turning performance (i.e., time to complete a turn, number of steps required to complete a turn, smoothness of performing the turn and balance control during a turn). Post-stroke individuals and healthy controls performed three tasks including overground straight line walking, a 90-degree turn and a 180-degree turn. The number of muscle modules during straight line walking were determined using non-negative matrix factorization. As few as two modules were found in post-stroke individuals. Differences in turning performance were only seen in the 180-degree turning performance measures. Those with two modules took longer to turn, used more steps and had less smooth movement. These results suggest obtaining independent modules should be an important aim in locomotor therapies aimed at improving turning performance. In addition, the time it takes to complete a 180-degree turn may be a useful clinical assessment measure of the degree of muscle coordination impairment post-stroke.