Postpartum depression (PPD) is a serious public health issue. Kangaroo mother care (KMC) is widely considered to be the most feasible, readily available and preferred intervention for decreasing neonatal morbidity and mortality in developing countries. We conducted a prospective study to assess the effect of KMC on PPD. The study population included 177 low-income mothers with their preterm infants. We used the validated Portuguese version of the Postpartum Depression Screening Scale for the assessment of maternal depression. The mothers were evaluated twice, at Neonatal Intensive Care Unit admission and at KMC discharge. We found 66 mothers (37.3%) with depression and it decreased to 30 (16.9%) after KMC intervention; p < 0.0001. None developed PPD during the Kangaroo stay. We concluded that KMC may lessen maternal depression. Further studies, may be required to clarify these preliminary findings.