The potential of human plasma (HP) or serum (HS) as a replacement for fetal calf serum (FCS) was evaluated in a liver infusion tryptose (LIT) medium for bulk cultivation of Leishmania donovani promastigotes. The promastigote yield with the LIT-FCS standard medium was 0.4-1.8×10(7) ml(-1), and yields of 0.5-3.4×10(7) (P = 0.527) and 0.4-2.4×10(7) (P = 0.062) were recorded for two LIT medium variants containing HP or HS as supplement instead of FCS. Significantly, higher promastigote yields of 1.3-4.9×10(7) ml(-1) were demonstrated when LIT medium was supplemented with HP of blood group O but not A, B, AB or equally pooled ABO (P = 0.007-0.020). Matching (P = 0.56) strong positive (1 : 10 2400 to ≥1 : 262 144 00) and weak negative (1 : 5-1 : 160) direct agglutination test (DAT) titres, respectively, were demonstrated in 24 visceral leishmaniasis (VL) and 45 non-VL sera for both standard LIT-FCS and alternative LIT-HP derived antigens. Our findings indicate strong potential for sustainable production of promastigotes for important diagnostic procedures such as DAT in the VL affected areas.