Analysis of adrenocortical function in acutely ill, hospitalized patients can be challenging due to changes in plasma binding proteins. This study used dynamic testing of salivary cortisol levels to evaluate adrenal function in hospitalized patients with low/low-normal plasma protein concentration in whom adrenal insufficiency was suspected. Twenty-eight patients with low serum albumin and proteins hospitalized for acute illness were evaluated for decreased adrenocortical function because of clinical presentations suspicious for adrenal insufficiency. Baseline and post cosyntropin-stimulated levels of serum total and salivary cortisol levels were assessed. Data were gathered by a retrospective analysis of medical records. Eight patients had normal peak serum total and salivary cortisol responses, consistent with intact adrenocortical function. Five patients had abnormal peak serum total and salivary cortisol responses indicating decreased adrenocortical function. Fifteen patients had subnormal peak serum total cortisol, but normal peak salivary cortisol responses indicating normal adrenal function. Salivary cortisol testing can identify hospitalized patients with apparently intact adrenal function in whom low serum protein confounded interpretation of serum total cortisol measurements. Salivary cortisol is a clinically useful surrogate for serum free cortisol in dynamic testing of adrenocortical function.