Touch screens are popular input methods for mobile devices, but they compete for visual attention with users' real-world tasks, leading to performance hindrances. In this study, we investigated the effect of an attention-saturating task on eyes-free gestures. A user study was conducted with 13 participants who performed eyes-free gestures on a smartphone using their dominant or non-dominant hand, alone or while performing a primary task that saturates attention. The results indicated that performing another task while drawing a gesture shortened the length and size of the gesture, reduced the duration of gesture entry, while the finger maintained the same speed across the touchscreen. Additionally, drawing a gesture with the nondominant hand increased the length of the gesture but generated less directional movements around the z-axis.