To investigate the association between night waking frequency in 3- to 4-month-old infants and mothers' response to them. Cross-sectional survey. We examined 663 mothers of infants aged 3-5 months who attended regular health checks for 4 months at 7 public health centres in Japan between September 2006 and March 2007. Mother-reported questionnaires were used, measuring the frequency of infants' night waking and four types of responses by mothers. Using multiple regression, the association between number of wakings and each response was evaluated adjusting for covariates, that is mother's (e.g. feelings of worry and bed-sharing) and infant's (e.g. age and sex) demographic variables. The number of wakings was related to "immediately feeding and/or checking diapers" (β = 0.16, p = .002).This response to infants' night waking may be associated with night waking frequency. Modifying caregiver responses to infants' night waking by reducing immediate feeding or diaper checks could improve infants' night waking frequency.