The purpose of this study was to test the effectiveness of a telephone intervention to reduce fatigue and the resulting symptom distress of mothers in Iceland who reported having a behaviourally difficult infant of 2-3 months of age. A sample of 78 mothers who reached distress criteria of depressive symptoms and parental stress was selected and randomly allocated in a controlled experimental study. In a brief intervention both maternal distress and infant difficulty were discussed. Results indicate a significant (P < 0.001) intervention effect on fatigue and its side-effects. It is concluded that intervention by telephone can be effective with fatigued mothers caring for a difficult infant.