Challenging environments (e.g., walking on inclines) are potential interventions for maintaining balance and gait skills, especially for the elderly. The aims of this study were: 1) to investigate whether or not variability and control of minimum toe clearance (MTC) is altered during walking on sloped surfaces, and 2) how locomotor control strategies change with age. MTC data during walking on a treadmill at both positive and negative slopes were analyzed for 9 healthy young and 8 healthy elderly subjects. The results indicated that altered MTC variability, complexity and control strategies were employed by the young and elderly adults due to walking on sloped surfaces. Elderly adults are more prone to tripping risk than younger adults especially while walking on positive slope.