Abstract Commercialisation of helmeted guinea fowl production in Africa is still in its rudimentary stage and there is a dearth of information on the optimal stocking density of the birds. This study was conducted to evaluate the effect of stocking density on the physiological responses and performance of guinea fowl. A total of 240 indigenous guinea fowl were used for this study. The birds were weighed and assigned to different stocking densities of 14, 16, 18 and 20 birds/m2 (SD1, SD2, SD3 and SD4, respectively) at four weeks of age. Feed and water were provided ad libitum. Data were collected on growth performance, haematochemical profile and plasma triiodothyronine of the birds. The results showed that from the 7th to the 13th week, birds stocked at 14 and 16 birds/m2 were significantly (P < 0.05) heavier than birds stocked at 18 and 20 birds/m2, while at weeks 14 and 15, body weight of the birds was in the order 14 birds / m2 > 16 birds / m2 > 18 birds/m2 > 20 birds/m2. Feed conversion ratios of the birds increased with stocking densities. Heterophil/lymphocyte ratio significantly increased with stocking density. It was concluded that stocking density of helmeted guinea fowl higher than 16 birds/m2 adversely affected growth performance and welfare of the birds.