Abstract: This study was done to investigate the prevalence of Oestrus ovis

of Awassi sheep herds in the northern region of West Bank (Palestine). A

slaughterhouse survey was performed from March 2006 to February 2007; a

total of 335 Awassi heads were examined. Oestrus ovis were found in 181

sheep out of 335 (53. %). The highest rates (P<.05) of infection were in the

months of June, July, August and October (77, 80, 82, and 73%, for these

months, respectively). The mean percent of larvae (L) in infected sheep heads

was 46 with L1, 30 with L2 and 23 with L3.

O.Ovis infestation is wide spread in the studied area. Measures must be

applied continuously in order to decrease the incidence of the infestation on

local herds.