More than two thirds of employees (67%) come to work when they are sick because they are worried about what their boss will think if they stayed at home.
According to part one of the Britain at Work study by research firm TNS, a 73% of UK employees, meanwhile, come to work because they feel that they have too much work to do.
In addition, more than half of respondents (54%) do not want to call in sick to work because they feel that it can affect their chances of promotion.
Gemma Camp, head of stakeholder management at TNS, said: "This sends an alarming message to employers around working cultures and the pressure they are putting on their employees.
"If staff are so concerned about what their boss might think, that they don't dare to take time off when they're sick, they risk not only their and their colleagues' physical health, but also their mental health. These results show that there is a widespread fear among British employees to be seen as slacking off, even though we know that the British work the longest hours in Europe and have the fewest days of annual leave."