Doppler transmitral flow velocities have been used to assess left ventricular diastolic function. Associations of transmitral velocities with specific physiologic variables and cardiovascular risk factors have not been reported previously in a large population-based study of young adults. We performed Doppler analysis of left ventricular inflow in 3492 black and white men and women (aged 23 to 35 years) in the year-5 examination of the Coronary Artery Risk Development in Young Adults (CARDIA) Study. First third filling fraction, peak flow velocity in early diastole (PFVE), peak flow velocity in late diastole (PFVA), and the PFVA/PFVE ratio were measured. Women had higher PFVE and PFVA than had men (PFVE: 0.81 +/- 0.13 m/sec versus 0.76 +/- 0.13 m/sec; PFVA: 0.47 +/- 0.11 m/sec versus 0.43 +/- 0.10 m/sec; both p < 0.001). Gender-specific multiple regression analyses showed that age, heart rate, systolic blood pressure, left ventricular percent fractional shortening, and body weight were independently and positively related to PFVA (all p < 0.001) in men and women. Age, heart rate, and forced expiratory lung capacity in 1 second were inversely related to PFVE and first third filling fraction (both p < 0.01). Left ventricular percent fractional shortening was positively related to PFVE and first third filling fraction (p < 0.001). Age, heart rate, and body weight were positively correlated with the PFVA/PFVE ratio (all p < 0.001). Height had weak negative associations with PFVA and PFVE in women only. These results suggest that, in young adults, Doppler measures of left ventricular diastolic filling are related to age, sex, body weight, blood pressure, heart rate, left ventricular systolic function, and lung function.