This cross-sectional study was performed among 150 senior staff nurses of Sylhet MAG Osmani Medical College during from September to December 2019 to assess the knowledge of nurses about hypertension. The maximum age of the respondents was 51 years and the minimum age was 25 years. The maximum respondents 77 (51.33%) were in 35-45 age group. The prevalence of hypertension among the relatives of senior staff nurses was about 33%. Of them 12% told that there was a history of hypertension among their mothers, 7.3% told the history of hypertension among their fathers, Sisters 3.3%, Brothers 2.7% and uncles. The mean age of the respondents was 37.39 ±5.24years. The educational qualification revealed that the majority had SSC (74.7%). and HSC, Degree and masters were 17.3%, 7.3% and .7% respectively. The professional qualifications of the respondents found that 131(87%) were Diploma in nursing and Diploma in midwifery, 10.7% were BSC nursing and only 2% were MPH holders. The majority 98.7%were responded hypertension was genetic, only 1.3% told hypertension was not genetic. The majority (81.3%) of the respondents told that it was a disease in blood vessel, 14.7% told it was a heart disease and only 3.3% told that it was a Brain disease. Knowledge on types of hypertension, 93.33% (n-150) told Primary &Secondary hypertension, only 6.66% told all three types of hypertension. 99.3% had knowledge about essential hypertension while only .7 had no knowledge about essential hypertension. Majority (49.33%) of the respondents told Genetic, smoking, Diabetes, Smoking, Kidney disease, overweight, High intake of fat containing diet, physical inactivity, anxieties, excess salt intake, Drug addiction were the causes of hypertension. 48.66% told Genetic, smoking, Diabetes were the causes of Secondary HTN, 23.33% anxieties, excess salt intake, Drug addiction. Problems of uncontrolled hypertension were showed that majority 93.3 % of the respondents told headache, neck pain, vertigo, nausea, restlessness, chest compression were the problems caused by uncontrolled hypertension. 98.0% told Genetic, smoking, Diabetes, anxieties, excess salt intake and overweight were the personal factors caused by HTN. Knowledge about the grade of hypertension was found that 95.33% told grade-1 and grade-2 hypertension and only 4.66% had known all three types of hypertension. Results showed that 99.3% (n=149) had told exercise, control body weight, change food habit, medication and stop smoking were the control measures of HTN. 65.3% told containing diet, control HTN. Related diseases avoid anxieties, increase intake of vegetables and fruits were the preventive measures of HTN. The insignificant association was found between age of the respondents and knowledge about preventive measures of hypertension. (p value> .05).