Thespectacular advances inneonatal surgery duringthelast20yearshavesolved manyproblems whichinthepastseemedunsurmountable. The advances have,however, raised manyproblems, amongstwhichperhaps themostimportant are thoseassociated withthesurgery ofpremature infants. Thispaperispresented inthehopeof throwing somelight uponthemanydifficulties which beset thesurgeon operating uponthese tiny infants. Itisnotsuggested thatwehavesolved these problems; wehavenot.Ouroperative mortality isvery highindeed. We hope, however, thatthis descriptionofourmaterial andourdifficulties will stimulateothers toimprove thepresent-day methods so thatinthefuture thesurgery ofpremature infants will beassafe asthesurgery offull-term infants is today. Atthepresent timeanoperation forasingle congenital malformation demanding urgent treatment inafull-term infant isrelatively safe.Itistruethat whenstudying thereports oflarge series operated uponinvarious Anglo-Saxon andEuropean centres wefindthattheoperative mortality fornewborn infants isnotinconsiderable; this isduetotwomain reasons, prematurity andmultiple malformations. We believe thattheoperative mortality forinfants suffering frommultiple severe malformations will remain veryhigh.Moreover, evenifthese infants survive, theydonotusually growuptobecome healthy children, butarefrequently moreorless crippled forlife. Prematurity isquite different. If thepremature infant survives operation heislikely todevelop aswellornearly aswellasafull-term child operated uponforthesamecondition. Itis todaywellknownthatevengrossly premature infants maydevelop into psychologically andphysically normaladults. Hess(1953), who followed up premature infants overseveral decades, foundthat 370infants withbirth weights ofunder1,250 g. (2lb.11oz.) whoweredischarged fromhisunit couldbetraced. Only5%ofthemhaddied.Of theothers, 85%wereofaverage oraboveaverage physical development and90%wereofaverage or * A paperreadatameeting oftheBritish Association ofPaediatric Surgeons heldinEdinburgh inJune, 1957. aboveaverage mental development. Thereisthereforelittle doubtthatitisworthwhile toundertake operations inordertosavethelives ofpremature infants. Incidence Isthequestion ofprematurity inneonatal surgery ofpractical importance? How often isitencountered?Theliterature seemstoindicate thatoperationson premature infants arerare.Surgeons record oneortwocases ascuriosities andonlyone extensive series ofoperations onpremature infants hasbeenpublished. Thisistheremarkable series reported fromtheBostonChildren's Hospital. In this world centre ofpaediatric surgery, 159prematiure infants wereoperated uponoveraperiod of16 years, i.e., anaverage ofabout10premature infants every year.Ifthese figures represent thetrueincidenceofprematurity inneonatal surgery, thenthe problem isnotworthmuchconsideration. We weretherefore surprised tofindanextraordinarily high incidence ofprematurity amongst the infants operated uponinourneonatal surgical unit atAlderHeyChildren's Hospital (Table 1).