The behaviors and medical problems in 27 persons with CHARGE syndrome were studied, because it was hypothesized that their behavior might be partly dependent on the heterogeneous medical status. With the exception of more tics, cardiac surgery was associated with positive behaviors: less withdrawn behavior, better mood, and a more easy temperament. Tube feeding was also related to positive behavior, since participants with a history of tube feeding showed less intense behavior. Cerebral deficits were associated with three problem behaviors: more intense and withdrawn behavior and a worse mood. Deaf-blindness was associated with developmental delays in expressive and overall communication level, and recurrent middle ear infections correlated with delays in written language. Of all medical conditions, only the presence or absence of heart defects and cardiac surgery could differentiate between the participants with regard to the number of behavioral problems. Participants with heart surgery especially, had less behavior problems. The number of operations and hospitalizations was not associated with behavior, but the total length of the hospitalizations was. Long hospital stays were associated with less problem behavior, especially internalizing behaviors. Cerebral and heart problems did not result in longer hospital stays, whereas esophageal reflux did. Age effects were reflected in older participants, who showed more internalizing problems. Heart surgery and hospitalization may be protective factors, but the protection might not be the actual surgery or hospital stay, as there may be other variables that are the actual cause, such as reduced vitality or altered parent child interactions after heart surgery. The study could not confirm a significant association between medical conditions and autism found in previous studies.