McManus drank heavily and, after several years of declining health, died from an alcohol-related illness. He was hospitalised with severe jaundice in May 1994, and died in Glasgow of pneumonia brought on by liver failure, on 6 June 1994, aged 59, only eight months after the death of his second wife Marion. In the last two years of his life McManus had also lost his mother, his brother and his two sisters. The actor was the first person to be posthumously awarded the Lord Provost of Glasgow's Award for Performing Arts.