Mothers who must express milk for a prolonged period frequently report that milk volumes decrease. The purpose of this pilot study was to assess the feasibility of having a sample of lactating mothers of preterm infants follow a specific breast pumping protocol, express milk mechanically for six weeks, and have a subsample consent to venipuncture. This pilot study compared the effects of pumping breasts sequentially or simultaneously on milk volume and prolactin levels in mothers of preterm infants. Nine lactating mothers were randomly assigned to a sequential single or simultaneous double electric breast pumping system. Prolactin levels were examined in four mothers on days 21 and 42 postpartum. The sequential single and simultaneous double groups had mean baseline prolactin levels of 50.8 ng/ml and 40.6 ng/ml, respectively on day 21, and 26.6 ng/ml and 34.5 ng/ml, respectively, on day 42 postpartum. At 9 and 12 weeks postpartum mothers were queried about their lactational status. The results suggested that milk yield may be maintained or increased with frequent use of the simultaneous double pumping system. Further study is needed to confirm results of this pilot study.