The pharmacokinetics of antipyrine were studied in 12 healthy volunteers and 10 patients of Kenya African origin with Hodgkin's lymphoma. The half-life of antipyrine was 12.2 +/- 1.3 h (mean + s.d.), while the apparent volume of distribution (V) was 0.67 +/- 0.11 l kg-1 (mean +/- s.d.) and the total body clearance was 40.7 +/- 3.2 ml kg-1 h-1 (mean +/- s.d.) in the healthy volunteers. The antipyrine half-life in the patients with advanced Hodgkin's lymphoma was 17.1 +/- 2.7 h (mean +/- s.d.). The apparent volume of distribution was 0.72 +/- 0.14 l kg-1 (mean +/- s.d.) which was larger than in healthy volunteers (P less than 0.05). The total body clearance was 30.3 +/- 9.4 ml kg-1 h-1 (mean + s.d.) and this was reduced compared with that in healthy volunteers (P less than 0.02). After cytotoxic therapy the half-life in the patients with advanced Hodgkin's lymphoma was significantly decreased to 8.3 +/- 1.3 h (mean +/- s.d.) (P less than 0.07), and the apparent volume of distribution was reduced to 0.65 +/- 0.07 l kg-1 (mean +/- s.d.) (P less than 0.05) while the total body clearance increased to 52.8 +/- 5.5 ml kg-1 h-1 (mean +/- s.d.) (P less than 0.01).