Diarrhea causes 16% of all child deaths in Pakistan. We assessed patterns of healthcare use among caretakers of a randomly selected sample of 959 children ages 0-59 months in low-income periurban settlements of Karachi through a cross-sectional survey. A diarrheal episode was reported to have occurred in the previous 2 weeks among 298 (31.1%) children. Overall, 280 (80.3%) children sought care. Oral rehydration solution and zinc were used by 40.8% and 2%, respectively; 11% were admitted or received intravenous rehydration, and 29% sought care at health centers identified as sentinel centers for recruiting cases of diarrhea for a planned multicenter diarrheal etiology case-control study. Odds ratios for independent predictors of care-seeking behavior were lethargy, 4.14 (95% confidence interval = 1.45-11.77); fever, 2.67 (1.27-5.59); and stool frequency more than six per day, 2.29 (1.03-5.09). Perception of high cost of care and use of home antibiotics were associated with reduced care seeking: odds ratio = 0.28 (0.1-0.78) and 0.29 (0.11-0.82), respectively. There is a need for standardized, affordable, and accessible treatment of diarrhea as well as community education regarding appropriate care in areas with high diarrheal burden.