Over twenty five years ago epidemiological studies revealed that there was a relationship between patterns of early growth and subsequent risk of diseases such as type 2 diabetes, cardiovascular disease and the metabolic syndrome. Studies of identical twins, individuals who were in utero during periods of famine, discordant siblings and animal models have provided strong evidence that the early environment plays an important role in mediating these relationships. Early nutrition is one such important environmental factor. The concept of early life programming is therefore widely accepted and the underlying mechanisms starting to emerge. These include: (1) Permanent structural changes in an organ due to exposure to suboptimal levels of essential hormones or nutrients during a critical period of development leading to permanent changes in tissue function (2) Persistent epigenetic changes such as DNA methylation and histone modifications and miRNAs leading to changes in gene expression. (3) Permanent effects on regulation of cellular ageing through increases in oxidative stress and mitochondrial dysfunction leading to DNA damage and telomere shortening. Further understanding of these processes will enable the development of preventative and intervention strategies to combat the burden of common diseases such as type 2 diabetes and cardiovascular disease.