Growth and ageing constitute a continuing process which involve genetics, oxidative metabolic damage, risk factors, pathology and which intervene greatly on functioning and disability in the daily life in the elderly. The interactions between these determinants have also to be considered within specific economic and cultural environments which tailor each individual life cycle, from early death to disabled survival, healthy or successful aging. More than 70 % of human genes contribute to determine longevity. The telomers' lengths differ considerably between gender. Good and bad genes at early or late expression modify the ageing process from healthy to pathology. The free radical theory of the aging process is based on the hypothesis that with increasing age, mutations of the mitochondrial DNA will accumulate and lead at last to a loss of function with subsequent acceleration of cell death. Positive (good gene, physical activity…) and negative risk factors (overweight, smoke, alcohol…) interfere with the ageing process itself and related diseases. Progressive or acute onset of disease can disrupt the life cycle. Acute diseases are lesser involved in death. Chronic diseases are more and more frequent, difficult to treat and badly tolerated. Chronic diseases are the main causes of the disablement process. Locomotor and mental disabilities are the more frequent far before cardiovascular, diabetes or sensory ones. The analysis of this ageing process will not be complete without stressing the major impact of the individual well-being. The quality of life is one of the most complicated part of human sciences. Whatever the scientist efforts its evaluation stays very approximate. The tufted complexity of the life process can easily explain how it is difficult to promote primary health prevention. The will, the drive, the anticipation ability change considerably the perception of life… Healthy ageing is perhaps a good thing for the individual and for the society but the best process is undoubtedly a successful ageing with a good appreciation of what the individual did during his life, the absence of remorse and desire for himself and for his affective surrounding to continue his society involvements and projects of life.