Background: Intestinal parasitic infections are major public health problems in several tropical and subtropical developing countries with poor socio-economic status including Ethiopia. Diarrheal patients are a major part of the population with a high risk of intestinal parasitosis. There is a scarcity of studies on intestinal parasite infection among diarrheal patients in South Gondar. As a result, this study was conducted to assess the prevalence and associated factors of intestinal parasite infection among diarrheal patients in this area. Methods: An institutional-based cross-sectional study design was conducted from March to May 2019 with a structured questionnaire data collection technique. A total sample of 240 diarrheal patients included in the study and a simple random sampling technique was used. The stool sample from each study subject was collected and analyzed by direct wet mount techniques. Data were entered in Epi Data Version 4.6.0.0 and exported to Stata version 14 for analysis. Binary logistic regression was used to measure the association of factors with the outcome variable. Factors that have an association with the outcome variable at p-value 0.25 was taken into the multivariable logistic regression analysis to control the potential confounders. The result of the final model will be expressed in terms of adjusted Odd Ratios (AOR) and 95% confidence interval (CI) and statistical significance will be declared if the P-value is less than 0.05. Results: The overall prevalence of intestinal parasitic infections among 240 diarrheal patients was 45.4%. The majorities of the positive cases were single infections (85.2%) while the remains were double infections (14.8%). Among the intestinal parasitic infections Entamoeba histolytica/dispar (E. histolytica/dispar) was the highest 60 (55.5%), and followed by Giardia lamblia (G. lamblia) 26 (24.1%), Ascaris lumbricoides (A. lumbricoides) 4(3.7%), hookworm4(3.7%) and Enterobius vermicularis 4(3.7%). The presence of intestinal parasitic infections had significantly associated with marital status (AOR: 0.41; 95% CI: 0.18,0.91).),shoe-wearing habit (AOR:2.81; 95% CI:1.07,7.37) and fingernail cleanliness (AOR:5.12; 95% CI: 2.35,11.12). Conclusion: Intestinal parasitic infections were a highly prevalent health problem among populations in Lay Gaynte woreda. Poor hygiene of fingernails and no shoes wearing a habit were risk factors for intestinal parasites infection among diarrheal patients.