In India most childhood nutrition recommendations and interventions are still not focused on infants under 6 months. Secondary data analyses of National Family Health Survey-3 data from India were analysed to compare the prevalence of wasting, stunting and underweight in infants less than 6 months and 6–59 months. Our results revealed that wasting was higher (31%) in infants less than 6 months (P < 0.05) as compared with children between 6 and 59 months. Thirteen per cent of infants less than 6 months had severe wasting, 30% were underweight and 20% were stunted. Most infants (69%) were exclusively breastfed (EB) for the first 2 months, but exclusive breastfeeding dropped to 50% at 2–3 months and to 27% at 4–5 months. There was no statistically significant difference in wasting and stunting in the EB and not exclusively breastfed (NEB) groups. Significantly fewer EB infants were underweight (28%) compared with NEB infants (31%) (P = 0.030). However, among EB children, 29% had wasting and 21% were stunted. Eleven per cent of EB infants were severely underweight, 13% were severely wasted and 9% were severely stunted. Diarrhoea was significantly lower among EB infants compared with NEB infants (P < 0.05). We conclude that infants less than 6 months of age are vulnerable to suffer from acute severe malnutrition irrespective of their breastfeeding status and need to be seriously considered for inclusion in national guidelines for early detection and management of undernutrition.