The relationship between mother infant interactions and psychopathology in postpartum psychotic disorders has been recognised as being clinically important, however data in the field is sparse. The current study had two aims--firstly, to study the prevalence and nature of delusions towards the infant among mothers with postpartum onset severe mental illness and secondly, to study the association between delusional symptoms towards the infant and mother infant interactions. 108 consecutive women with onset of severe mental illness in the postpartum, who were admitted to an inpatient psychiatric unit in South India over a two-year period, were systematically assessed for presence of delusions related to the infant, using the Kannada version of the Birmingham Interview for Maternal Mental Health. Fifty-three percent of subjects reported delusions related to the infant, with 34% reporting more than one delusion. Mothers with infant related persecutory delusions were more likely to show affectionate behaviour and had normal competence and caring for baby's basic needs; however, they were more likely to get disturbed and agitated if separated from the baby. Mothers who had delusions that the baby was a devil or ill fated or someone else's baby, were more likely to have significant abusive incidents towards the baby. Overall, the mothers who had delusions related to the infant were seen to have more significant abusive incidents and were more likely to be considered unsafe in looking after the baby alone. The study emphasises the need for systematic clinical assessment of psychopathology in mothers with postpartum psychosis.