The foetal adrenal gland comprises of two distinct zones; the foetal zone (FZ) and the smaller subcapsular definitive zone (DZ). The FZ produces large amounts of androgens used by the placenta during oestrogen synthesis and expresses cytochrome P450 enzymes, such as CYP21, involved in the synthesis of aldosterone and cortisol. The DZ has been proposed to contain a population of adrenocortical progenitors. These cells are thought to migrate centripetally, perhaps via the distinct columns of cells radiating from the inner layer of the DZ to the outer layers of the FZ, to populate the rest of the gland. This study aims to identify and characterise these cells. Murine studies have identified Sonic Hedgehog (SHH) pathway in a possible subcapsular non-steroidogenic progenitor population. Activation of this pathway has been implicated in the patterning of other developing endocrine glands however its involvement in the human foetal adrenal gland has yet to be defined. DAX1, dosage-sensitive sex reversal adrenal hypoplasia critical region on chromosome X gene 1, is known to inhibit steroidogenic factor 1 mediated steroidogenesis and murine studies show similar expression profiles to that of SHH. Hence DAX1 expression in the absence of steroidogensis could highlight a progenitor population. We therefore hypothesised that a human adrenal progenitor cell population may be identified using a combination of markers for adrenal DZ and the SHH pathway. To test this hypothesis a combination of reverse transcription PCR and immunohistochemistry was used to examine the expression of Sonic hedgehog, Smoothened (G protein coupled receptor of the SHH pathway), Gli1 (transcriptional activator of SHH pathway), CD56 (DZ marker), CYP21 and DAX1 mRNA and protein in the human foetal adrenal. Positive transcripts for each of the markers were observed from mRNA extracted from total foetal adrenals (n = ≥1). By immunohistochemistry both SHH and GLI1 showed positive signal at the periphery of the gland, in a similar region to CD56 (n = ≥1). DAX1 expression was also observed to be highest at the periphery of the gland but also localised with CYP21 in the FZ (n = ≥1). This study has identified a population of GLI1 and DAX1 positive cells which may be representative of an adrenocortical progenitor population. These findings will be advanced by further investigating the involvement of the SHH pathway in the proposed progenitor population. Cyclopamine, an inhibitor of SMO, will be used to assess the importance of the SHH pathway by its effect on the amount of Ki67 and CD56 positive cells in the DZ. Identification and characterisation of the human foetal adrenal progenitors will give a better understanding of gland development.