• Gordon Smith took over from David Taylor in 2007
Smith admitted personal reasons played a part in his decision but were not solely responsible gas he declared the time was right to step down after almost three years as chief executive.
Despite thanking the majority of people he had encountered for their approach towards him, the 55-year-old explained there had been a minority who had been "less than supportive".
In a statement released through the SFA, Smith said: "I have enjoyed my time with the Scottish FA immensely and feel privileged for having had the opportunity to play a leading role in one of the biggest and most high-profile organisations in the country.
"As has been reported in today's press, there are external factors that need my attention.
"Stepping down, though, is something I have considered for some time.
"The majority of people I have encountered during nearly three years in the job have been extremely warm, friendly and hospitable towards me.
"Inevitably, there has also been a minority who have been less than supportive."
Smith added: "This has been a difficult enough time, dealing with my mother being admitted to hospital after a fall.
"To compound matters, she is the carer for my father, who is seriously ill.
"It is not purely personal reasons, or the element of negativity I have experienced, that has made me leave the job.
"It is a combination of factors. Ultimately, I feel the timing is right."
• Read more in The Scotsman tomorrow