A study was conducted in Debre-Zeit town to determine the incidence of bovine clinical mastitisrnin a purposefully selected two dairy farms and the efficacy of conventional antimicrobial drugsrnand traditional herbs, from September 2003-March 2004. The objectives of the work were tornassess the invitro effect of six herbal preparations; namely, Brucea antidysentrica, Combertumrnmolle, Cyphostemma adenocale Persicaria senegalensis, Plantago lanceolata and Zehneriarnscabra on major isolates of clinical bovine mastitis, to compare their efficacy, with conventionalrnantimicrobial agents that are commonly used for the treatment of bovine mastitis, and torninvestigate the effect of the herbs on the growth inhibition of resistant isolates. The herbs wererncollected from their natural habitats and processed and extracted with 80% methanol. Bothrnabsolute methanol and aqueous extracts of Combertum molle were assessed foe antimicrobialrnproperty. Milk samples from clinical cases were collected aseptically and causal agents werernidentified after the severity of the diseases in each cow was categorized into Grade I-Grade III byrnfollowing standard laboratory procedures and finally sensitivity test was conducted onrnStaphylococcus aureus (n=17) and Streptococcus agalactiae (n=14), which were the predominantrnisolates. The incidence rate was 12.4 new clinical mastitis cases/ 100cows-month and 6.7 newrnclinical mastitis cases/100cows-month at risk in EARO and Fair-field dairy farms respectivelyrnwith an overall incidence of 9 new clinical mastitis cases/100cows-month at risk. Staphylococcusrnspecies (42.3%) and Streptococcus species (34.5%) were the major isolates from Grade I (84%)rnand Grade II (16%) clinical cases. Single infection of 46.8% and mixed 37.5% and contaminatedrn9.4% infections were recorded with 6.3% negative cultures. Staphylococcus aureus was resistantrnto Oxytetracycline (23.5%) and Penicillin G (64.7%) and Streptococcus agalactiae was resistantrnto Neomycin and Streptomycin (85.7% each) and Oxytetracycline (100%). Burcaernantidysentrica, Combertum molle, Cyphostemma adenocaule and Persicaria senigalensis wererneffective against susceptible and resistant isolates and among those absolute methanol extract ofrnCombertum molle showed a better effect on both test organisms. Plantago lanceolata andrnZehneria scabra were not showing visible inhibitory zone against test organisms. None of thernherbal extract preparations showed visible inhibitory effect on Escherichia coli. This studyrnindicated that mastitis is a great problem in the two dairy farms and resistant isolates arernVIIIrncirculating within farms. For this herbal preparations might be considered as an alternative optionrnfor the treatment of resistant isolates of clinical bovine mastitis for the future.rnKeywords: Clinical mastitis, herbal preparations, aetiological agents, Staphylococcus aureus,rnStreptococcus agalactiae, sensitivity, effect, conventional antimicrobials and resistant isolates