A total of 70 lambs aged from three days to 2 months were used in this study, 60 lambs showed symptoms of diarrhea while the remaining (10) lambs were healthy and used as control. The animals were belonged to a variable breeding model large farm, small holder and individually owned in Bohaira province. This work aimed to study some etiological agents, bacterial and parasitic, and studying the subsequent affects on some biochemical parameters. The bacteriological results revealed that. Ecoli, Klebsiella, Enterobacter Citrobacter, Proteus, Serratia spp and Morganella morganii as members of Enterobacteriaceae were detected in incidences of 43.3, 16.6, 15, 13.3 13.3, 8.3 % respectively. Pseudomonus aerogeneosa, Staph. aureus, Strept. ini and Enterococcus fecalis were detected in an incidences of 8.3, 13.3, 3.3 and 6.7 % respectively, the incidences were varied in variable breeding size. The parasitic investigations revealed 83.3 % positive samples 70% for Eimeria spp. by flotation technique and 18.3 % for Cryptosporidium spp. by modified Zeiehl Nelson technique, 65 % of cases were infested with Eimeria spp. Oocysts alone, 13.3 % of cases revealed Cryptosporidia parvum separately and 5 % were harboring mixed parasites all were coincide with bacterial infection. Seven spp. of Eimeria were identified by fecal culturing.           E. crandalis was the most common one. Sensitivity tests were carried for some of important and predominant isolates of bacteria. All members of the isolated Enterobacteriaceae strains were biochemicaly identified. The biochemical alterations accompanied with diarrhea including changes associated with bacterial, Coccidian, Cryptosposidia infections singly or mixed in relation to apparently healthy were done. The economic importance,  health hazards and reduce incidences or combating the problem were discussed.