The proportion of nursing staff in their 50s and 60s has risen sharply in the past four years - from 30 per cent in 2010 to 35.3 in 2013.
Opposition politicians and nursing leaders warned that plans needed to be put in place now to increase nurses in training and help older staff carry on in their jobs.
The Scottish Government said student places were increasing, while the number of NHS staff was also on the rise.
In 2010, figures revealed there were 20,174 nurses over 50 working in Scotland. By last year this had increased to 23,393.
The data also showed that 11.3 per cent of nurses were between 55 and 59 years old, 4.1 per cent were aged between 60 and 64, with 0.8 per cent over the age of 65.
The Scottish Conservatives said the figures, from Information Services Division (ISD) Scotland, meant thousands of nurses were now contemplating retirement, and would need to be replaced by either student nurses or staff from overseas.
They said it came at a time when nursing numbers had been cut across Scotland.
While the number of nursing and midwifery staff has increased since the SNP came to power in 2007 - up from 56,783 to 57,368 - it has dropped from a peak of 58,428 in 2009.
In the last year numbers have started to rise again, with more than 1,000 more nurses in September 2013 compared to the same time in 2012.
Call for more nurses
The Scottish Conservatives urged the SNP to increase the number of nurses being trained now to have enough ready to enter the profession when more started to retire and to deal with growing demand caused by the ageing population.
The party said there were 2,713 new entrants to the workforce last year which, while up on the previous year, was still significantly below other years.
Scottish Conservative health spokesman and deputy leader Jackson Carlaw said: “These figures show us that retirement will very much be on the mind of thousands of nurses.
“Now is the time to prepare for that, and increasing the number of young Scottish people training for this valued profession is the way to do it.
“It would be entirely regrettable if, several years down the line, we are forced to recruit nurses from all corners of the globe because of the short-sightedness of the Scottish Government.”
Royal College ‘raised concerns’
Theresa Fyffe, director of the Royal College of Nursing Scotland, said they had been raising their concerns for some time about how older nurses in the workforce will be replaced when they retire, as there was “no obvious plan” for replacing so many nurses in a relatively short space of time.
She added: “But we are equally concerned about how older nurses in the workforce are managed.
“Nursing is a fabulous career choice but it is hard work. While older nurses, with years of experience, can still make a significant contribution, the unique nature and demands of the job raise serious questions about plans to raise the retirement age for health care workers.”
The warnings come after Brian Keighley, chairman of the British Medical Association (BMA) Scotland, last week said doctors in Scotland were suffering “stress and burnout” as growing NHS workloads took their toll.
Government claim 2,400 extra staff
A Scottish Government spokesman said: “Under this Government, we have over 2,400 more nurses and medical staff in post. In the last year alone there has been an increase of 1,000 extra nurses, and over 250 more medical staff,” a spokesman said.
“Scotland also has a high number of student nurses, with 10,189 Nursing & Midwifery students in training at 2012.
“Every newly qualified nurse in Scotland is guaranteed one year of employment once they complete their studies, a commitment which not offered anywhere else in the UK.
“The Health Secretary has already announced a four per cent increase in student intake numbers from 2,430 in academic year 2012-13 to 2,530 in 2013-14.”