34 different cultures of fungi isolated from 185 clinicaly positive pneumonic cases of buffalo calves were tested for both toxicity and toxins production. About 60% of the isolates proved to be toxic to brine shrimp. Aspergillus was the most toxigenic to brine shrimp, 57% of its isolates were toxic to this test organism comparable with 50% in case of both Mucor and Penicillium. Thin layer chroma tographic analysis showed that 14 isolates produced known mycotoxins. Toxins identified are aflatoxin B1, B2, G1 and G2 produced by four isolates of A. flavus and one isolate of A. parasiticus, kojic acid by two isolates of A. fumigatus, citrinin by two isolates of P. notatum and sterigmatocystin by two isolates of A. nidulans and three isolates of A. terreus.