A total of 57 samples were collected from different environments (soil, water, and sewage samples) from different locations in Baghdad governorate. The total isolates obtained from these samples were 30 isolates, 15 of them were identified as Serratia spp according to cultural and morphological characteristics. Biochemical tests were carried out on these 15 isolates. Results showed that 5 of these isolates were identified as Serratia marcescens. The ability of these isolates in prodigiosin production was examined. Results showed that all these isolates are prodigiosin producers, among them S.marcescens S11 was the efficient one in prodigiosin production, the prodigiosin activity in culture medium of this isolate was 200 U/cell. Optimum conditions for prodigiosin production by S. marcescens S11 were studied. Results showed that the optimum conditions for prodigiosin production were achieved when the production medium supplemented with olive oil as a carbon source, and casein hydrolysate as a nitrogen source in a concentration of 1.5% for broth, KH2PO4 as a phosphate source, initial medium pH 8, and incubation at 28 C. Under these conditions, prodigiosin activity in culture medium was increased to 3000 U/cell. S. marcescens S11 was subjected to mutagenesis to increase its ability in prodigiosin production. Random mutagenesis was achieved using physical mutagen by UV irradiation, and chemical mutagen using Mitomycin C. Results showed that subjection of S. marcescens S11 to UV irradiation and Mitomycin C caused to obtain several mutants characterizedwith its high ability in prodigiosin production Prodigiosin activity culture medium of the most efficient over-producer mutant (S11H7) raised after physical mutagenesis was 350 U/cell, while the prodigiosin activity in culture filtrate of the most efficient over-producer mutant (S11H54) raised after chemical mutagenesis was 400U/cell in comparison with 200 U/cell for the wild-type.