Some things that can affect a child's nutritional status is poor food consumption and comorbidities such as infection. The infectious disease that often affects children under five suffering malnutrition include diarrhea, respiratory infections, tuberculosis, malaria and measles. The aim of this descriptive study was to describe the incidence of infectious diseases in children under five suffering malnutrition in Sub Sukorejo Working Area Health Center Sukorejo Ponorogo.
The design of this research is descriptive research design. While the population in this study were all mothers with infants suffered malnutrition Sukorejo infectious diseases in the district Ponorogo. The sample in this study using purposive sampling with 51 respondents. Collecting data using koesioner with open and closed answers.
From this study showed that 100% of children under five suffering malnutrition had also experienced infectious diseases. Of 3 infectious diseases that often suffered by 51 respondents showed them around the toddler had experienced ARI, toddlers who have had diarrhea as much as 82.4% and toddlers who have had measles by 21 , 6%.
To prevent the occurrence of infectious diseases, especially in children under five suffering malnutrition is expected that the mother is more concerned about the fulfillment of essential nutrients in the growth and development of children, by improving nutrition in infants so that no infectious disease and avoid the occurrence of malnutrition.

Keywords: infectious diseases, malnutrition