The records of 141 consecutive patients with proven tuberculosis (TB) were reviewed to examine for changes in their serum proteins, erythrocyte sedimentation rate (ESR) and tuberculin skin test reactivity. Hypoalbuminaemia was present in 73% of patients and hyperglobulinaemia was seen in 92% of patients. ESR showed a negative correlation with the serum albumin level but a positive correlation with the serum globulin level. In the case of pulmonary TB, ESR was higher in patients with radiologically more extensive disease. Tuberculin reactivity was reduced in patients who were older, those with more severe hypoalbuminaemia and those with disseminated TB. KEYWORDS: Albumin, erythrocyte sedimentation rate, globulin, tuberculin reactivity, tuberculosis