Protease activity of Aspergillus niger growing on solid substrate correlated well with conidia formation (R: 0.91-0.96) for initial moisture contents of 38-48% (wet basis), initial pH 5.4 and 6 and temperature (29-37 degreesC ). However, conidia/protease ratio varied with most of these conditions and by NaCl addition indicating only a partial association between them.