There is a paucity of information on the reproductive biology of guinea hens. A study was conducted to document postembryonic developmental changes in the ovarian histology and associated progesterone and 17β-oestradiol profiles until 32 wk of age (WOA). Highly significant increases (P < 0.001) were noticed in oocyte and follicular diameters beyond 16 WOA. Other ovarian follicular morphometric traits showed inconsistent increases until 16 WOA. The first phase of yolk deposition occurred between hatching and 20 WOA, the second phase between 20 and 26 WOA, and the third and final phase between 27 and 28 WOA. Peripheral 17β-oestradiol concentrations increased from 20 WOA until it peaked at 28 WOA, whereas peripheral progesterone concentrations fluctuated considerably during sexual development. Both oestradiol and progesterone concentrations were negatively and moderately correlated (P < 0.01) with oocyte nuclei diameter, granulosa and theca layer heights. However, oestradiol concentrations were positively and strongly correlated (P < 0.001) with oocyte and follicular diameters, and moderately with progesterone concentrations. Three phases of yolk depositions were found in the guinea hen, with the final phase terminating at 28 WOA, at a much smaller oocyte diameter than in the domestic chicken. Oestradiol might play a role in yolk deposition in this species.