Background Sagittal abdominal diameter (SAD) is an anthropometric index associated with visceral adiposity. It remains unclear whether SAD and its socio-economic correlates differ in women and men, which limits the epidemiological and clinical applications of the SAD measurement. The aims of this study are to examine the sex differences in SAD and its socio-economic correlates. Methods A complex stratified multistage clustered sampling design was used to select 6975 men and 7079 women aged 18 years or more from the National Health Nutrition and Examination Survey 2011–2016, representative of the US civilian non-institutionalized population. SAD was measured in accordance to the standard protocols using a two-arm abdominal caliper. The sex differences in SAD and its socio-economic correlates were evaluated by performing weighted independent t tests and weighted multiple regression. Results SAD was lower in women than in men in the entire sample, as well as in all the subgroups characterized by age, race, birth place, household income, and body mass index except for non-Hispanic blacks and those with household income< 20,000.Adjustedforothercharacteristics,age,birthplace,householdincome,andbodymassindexwereassociatedwithSADinbothwomenandmen.BlackwomenwereassociatedwithhigherSADthenwhitewomen(p<.0001),andHispanicandAsianmenwereassociatedwithlowerSADthanwhitemen(bothp<.01).WomenborninothercountriesweremorelikelytohavelowerSADthanwomenbornintheUS(p<.0001),andsoweremen(p=.0118).Bothwomenandmenwithahouseholdincomeof< 75,000 had higher SAD than those with an income of over 75,000.Theassociationsofage,race,andhouseholdincomewithSADdifferedinwomenandmen.ConclusionSADislowerinwomenthaninmen,inthegeneralpopulationaswellasinthemostsocio-economicsubgroups.Whilesocio-economiccorrelatesofSADaresimilarinwomenandmen,theassociationsofage,race,andhouseholdincomewithSADvaryacrosssex.