During March-May 1990, in-depth interviews were conducted with 200 women who first accepted the injectable contraceptive depo-medroxyprogesterone acetate (DMPA) between July and August 1988 from the Maternal and Child Health and Family Planning program of the International Centre for Diarrhoeal Disease Research, Bangladesh in the rural Matlab district. The researchers analyzed the data to examine the determinants of first-time use durations of DMPA. 90% of the women chose DMPA because of negative experiences or fears of such experiences with other methods. Women who reported bleeding and nonbleeding side effects were more likely to have shorter use durations than those who reported no side effects (rate ratio [RR] = 1.83 and 3.07, respectively). Women who had heavy bleeding had the shortest use duration (median, 9 vs. 20 months for no problems). Amenorrhea was rarely considered to be the most significant problem linked to DMPA use. Women who chose DMPA because of its perceived positive aspects were more likely to have longer use duration than those who did not choose it for its positive aspects (RR = 0.38). Women who chose DMPA based on the community health worker's advise were more likely to have shorter use durations than those who did not choose it based on their advice (RR = 2.48). Women whose husbands approved of family planning were more likely to have longer use duration than those whose husbands did not approve (RR = 0.72). Multiparous women used DMPA longer than did those with less than 3 children (RR = 0.56 for 3-5 children and 0.36 for =or 6 children). These findings emphasize the importance of considering side effects in a social and cultural context to determine why they are important to women and which side effects are perceived as problematic and which are not. They also show the need to improve pre-use counseling and side effect management and to seek the support of husbands towards family planning.