Two people are currently being treated at Wishaw General Hospital after contracting swine flu.
Swine flu can be lethal and claimed the lives of more than 200 patients in the UK during an outbreak in 2009.
Symptoms include a high fever, tiredness, headaches and muscle pain or joint pain.
Both patients have been diagnosed with the H1N1 strain of influenza.
NHS Lanarkshire had not released any further details on the patients but said it had expected to see some cases as swine flue was “the main flu virus circulating in the community”.
Dr Femi Oshin, consultant in public health medicine at NHS Lanarkshire, said: “Although there are low levels of influenza overall this winter, H1N1, also known as swine flu, is reported to be the main flu virus circulating in the community.
“It is therefore to be expected that we will see some cases of H1N1 in Lanarkshire at this time.
“The seasonal influenza vaccination is the best way to protect yourself against flu, including H1N1.
“The annual flu vaccine is available free to pregnant women as well as other eligible groups including people over 65, those who have certain health conditions, healthy children aged two, three and four plus children in school years one and two, and people who work in healthcare.
“If you are in one of the eligible groups, one of the ways of getting vaccinated is by contacting your GP.
“We currently have two patients in Wishaw General Hospital with H1N1.”
Swine flu was first identified in Mexico in March 2009, and two Scots holidaymakers were among the first to be diagnosed weeks later.
The last recorded case in Scotland was in February 2014 when a campsite owner from the Isle of Skye died in Glasgow from the virus.