Subclinical hypothyroidism is linked to poor health. The effects of subclinical hypothyroidism on cortisol reactivity stress was examined in 54 healthy men and women aged 18-30 years. Participants with elevated TSH levels displayed significantly higher baseline cortisol levels. Cortisol levels increased among participants with normal TSH levels but decreased in response to stress among participants with elevated TSH levels. This cortisol decrease reflects dysregulated HPA-axis functioning known to be associated with depression and cognitive dysfunction.