Thirty-one isolates of the form genera Acremonium and Cephalosoporium were screened for their ability to excrete enzymes capable of degrading β-glucans. Most produced both (1 → 3)- and (1 → 6)-β-glucanases together, although the yields varied with carbon source used. Surprisingly, higher yields of (1 → 3)-β-glucanases were often seen from isolates grown on pustulan, a (1 → 6)-β-glucan which is not hydrolysed by these enzymes. Lower enzyme yields were generally obtained with glucose than with either laminarin, a (1 → 3)-β-glucan or pustulan as carbon sources, suggesting regulation of synthesis by either catabolite repression and/or induction. However, a few isolates, most notably Cephalosporium sp. OXF C13 and Acremonium strictum appeared to have some constitutive-β-glucanase activity. Most of the isolates screened were only very weakly cellulolytic against carboxymethyl cellulose or filter paper as substrates.