Potato late blight disease, caused by Phytophthora infestans is the major constraint of potato production in Ethiopia. A survey was conducted in North Wollo Administration Zone of the three districts (Meket, Wadla and Angot) to assess the importance of potato late blight. Field experiment was also conducted in Sirinka Agricultural Research Center trial station at Meket, during 2018 main cropping season to determine appropriate spraying frequency combined with different levels of resistance variety. The experiment had 15 treatments with a combination of three potato varieties (Belete, Gudene and Jalene) and five spraying frequencies (zero, one, two, three and four times spray. The experiment was laid out in randomized complete block design in factorial combination with three replications. The survey result revealed that in the study area the overall mean of incidence (48.20%), severity (23.68%) and prevalence (72.36%) of the disease was recorded. The average incidence (53.85, 66.5 and 30.33%) and severity (33.9, 33.37 and 7.5%) of potato late blight were scored in Meket, Wadla and Angot Districts respectively. The combination of potato varieties and spraying frequencies of Ridomil applications showed statistically significant disease, yield and yield component parameters. At 68 days after planting (DAP) the highest disease incidence (90%) was recorded from Jalene variety treated with zero spraying frequencies. Minimum disease incidence (56.67%) was scored from both Belete and Gudene varieties treated with three times spray. The highest disease severity at 96DAP (84.76%) was obtained from Jalene variety treated with zero spraying frequency. Highest tuber yield (29.62 t ha -1) was obtained from Belete variety treated with two-time spraying of Ridomil application. Whereas the lowest tuber yield (12.93 t ha-1) was recorded from Jalene variety treated with zero spraying frequency. The highest marginal rate of return (1774.65%) was obtained from Belete variety treated with one spray, followed by 1294.6 and 1010.8 % had been obtained from Gudene and Jalene varieties treated with two and four times spray respectively. Finally it is concluded that, for moderately resistance one time spray, for moderately susceptible two times spray and four times spray for susceptible varieties were found better management options and get highest cost benefit as compared with other treatment combinations. However, further extensive works have to be done for determining the importance and temporal distribution of the disease. And also needs further study on the management of the disease under different agro-ecologies for additional years to determine the best-integrated management options and to increase the production and productivity of potato in the country. Keywords: Disease progress rate, Incidence, Severity, Late blight, MRR, Percentage yield increase, Relative yield loss, Ridomil