How long does it take for methadone to leave your body?

Depends....: Cyp type enzymes are used to metabolize Methadone - everyone has different ratios and strengths to these enzyme types - thus the duration of effect from Methadone varies but is typically in the range of 8-72 hours.

Depends...: There is some variability to metabolizing Methadone in different individuals. It's effects can last from 8-72 hours.

Extremely variable: Methadone is lipid- (fat-)soluble and takes several days to fill tissue reservoirs after a person begins taking it. The rate at which methadone leaves a person's body after he/she stops it is variable and depends on dose, frequency, and on body chemistry. It can literally take months for some folks.