In the current study, 55 Penicillium species were screened for lectin activity using erythrocytes of human ABO, pig, sheep, goat and rabbit. Only four Penicillium species, namely P. duclauxii , P. griseoroseum , P. proteolyticum and P. caseifulfum exhibited lectin activity, while crude undiluted mycelial extract of six species ( P. aragonense , P. coralligerum , P. lagena , P. pinophilum , P. spinuloramigenum and P. miczynskii ) showed weak haemagglutination. P. duclauxii , P. caseifulfum and P. proteolyticum lectins demonstrated non-specific agglutination towards human as well as animal erythrocytes, whereas P. griseoroseum lectin displayed specific agglutination activity only towards rabbit erythrocytes. Neuraminidase and protease treatment of erythrocytes showed an increase in lectin activity of P. duclauxii , P. griseoroseum and P. proteolyticum , whereas no effect occurred on lectin activity of P. caseifulfum . Lectin activity expressed after 5 days of cultivation in broth cultures of P. griseoroseum and P. proteolyticum exhibited a sharp decline after the 8th and 9th day, respectively. In P. caseifulfum and P. duclauxii broth cultures, lectin activity was expressed after 6 days of cultivation and demonstrated decline after the 7th and 8th day, respectively. A panel of 40 carbohydrates and glycoproteins was used to study their minimum inhibitory concentration capable of inhibiting lectin-induced haemagglutination. Lectin activity of P. duclauxii , P. proteolyticum , P. caseifulfum and P. griseoroseum was strongly inhibited by chondroitin-6-sulphate, thiogalactoside, bovine submaxillary mucin, porcine stomach mucin and fetuin. Owing to their enormous ability to discriminate sugars with high specificity, a myriad of lectins can be used as biotechnological tools for future research.