Growth and reproductive performance traits are traits of economic importance for sheep selection and productivity improvement interventions. This study aimed at comparative evaluation of growth and reproductive performance traits of sheep in the highland and lowland agro-ecologies of northwestern Ethiopia. Data on growth performance traits were collected from 144 Washera (78 males and 66 females) lambs and 72 Gumuz (37 males and 35 females) lambs. Data on reproductive performance traits were collected from 260 Washera (130 rams and 130 ewes) sheep and 150 Gumuz (75 rams and 75 ewes) sheep. General linear model univariate procedure was employed to analyze the collected data. Breed, the interaction effect between breed and season of birth as well as the interaction effect between breed and type of birth all exerted very high significant effect (P<0.001) on live weight at all age groups. Breed type affected pre-weaning average daily weight gain significantly (P<0.01). Pre-weaning average daily weight gain of Washera (70 g/day) was found much better performance than 60 g/day of Gumuz. Breed type exerts significant (P<0.05) effect on age at first lambing, lambing interval, annual reproductive rate and number of lambs born per ewe life time. Average age at first lambing and lambing interval of Washera sheep were 11.69 months and 9.27 months, respectively. The corresponding values for Gumuz sheep were 12.51 months and 10.43 months, respectively. Production and reproduction performance values of traits varied across the two breeds and sexes as well. These values can be used to set up breeding objectives or goals for selective breeding of sheep giving special emphasis to growth traits believed to have medium heritability values.