The last years more studies are using non-linear dynamics to describe cardiovascular control. Because of the large dispersion of physiological data it is important to have large studies with both male and female participants to establish a range of physiological healthy values. This study investigated the effect of gender and age on non-linear indices. Non-linear scaling properties were studied using: 1/f slope, fractal dimension, and long- and short-term correlations (DFA₁ and DFA₂). Non-linear complexity was described with correlation dimension (CD), Lyapunov exponent (LE) and approximate entropy (ApEn). The population consisted of 135 women and 141 men (age: 18-71 yrs). Twenty-four hour ECG recordings were obtained using Holter monitoring. The recordings were split into day-time (8 AM-9 PM) and night-time (11 PM-6 AM). A day/night variation was present in all non-linear HRV indices, except for the CD in the female population. During the night the percentage of CD values of surrogate data files differing from the CD value of the original data increased. All non-linear indices were significantly correlated with age. Deeper analysis per age category of 10 years showed a stabilisation in the age decline of the FD and ApEn at the age of 40 or more. The vagal pathways seemed to be more involved in the generation of non-linear fluctuations. Higher non-linear behaviour was evident during the night. No clear difference between men and women was found in the non-linear indices. Non-linear indices decline with age. This can be related to the concept of decreasing autonomic modulation with advancing age.