Micronomicin is a new aminoglycosidic antibiotic discovered and developed by Kyowa Hakko Kogyo Co., Ltd. It is produced by Micromonospora sagamiensis var. nonreducans. Investigation of micronomicin performed in 134 research facilities in Japan led to the following results. 1) Micronomicin showed a broad antibacterial spectrum against Gram positive and Gram negative bacteria. 2) In susceptibility tests of clinical isolates, micronomicin was almost similarly active to GM. 3) Bactericidal activity of micronomicin against Pseudomonas aeruginosa and E. coli was higher than those of TOB and DKB. 4) Micronomicin showed a synergistic antibacterial activity against Pseudomonas aeruginosa and E. coli with CBPC and SBPC. 5) The therapeutic activity of micronomicin in mice infected with Pseudomonas aeruginosa and Serratia sp. was in high correlation with in vitro antibacterial activity similarly to that of GM. Micronomicin (sold under the brand names Sagamicin and Luxomicina among others) is an aminoglycoside antibiotic, and like others in its class, binds to the ribosomes of non-resistant cells causing mistranscription of mRNA which fatally inhibits production of essential proteins. Micronomicin sulfate can inhibit bacterial protein synthesis, while destroy the bacterial cell wall. Micronomicin has an antibacterial activity against gram-negative and gram-positive bacteria such as Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Shara, Escherichia coli, etc. Streptococcus pneumoniae and Pneumococcus are sensitive to it, but its activity on anaerobic bacteria and some hemolytic streptococcus is weak.