Background The number of trips to the tropics taken by children with chronic health disorders (CHDs) is increasing.

Methods All of the children with CHDs who attended two international vaccination centres in France before travelling to the tropics were included in a prospective, exposed/unexposed study. Each child was age-matched with two control children and followed for 1 month after returning from the tropics.

Results Fifty-six children with CHDs and 107 control children were included. The children's median age was 6 years old (IQR 2–11). Of the study participants, 127/163 (78%) travelled to West Africa, mainly to visit relatives. The median duration of the stay was 42 days (IQR 31–55). The age of the children, the destination and the duration of the trip were similar between the two groups. Sickle cell disease (23/56) and asthma (16/56) were the most common CHDs. Overall, the children with CHDs experienced more clinical events than the control patients did (p<0.05); however, there was no difference when chronic disease exacerbations were excluded (p=0.64) or when only the period abroad was considered (p=0.24). One child with a recent genetic diagnosis of atypical haemolytic uraemic syndrome died from a first disease exacerbation.

Conclusions Health problems among children with CHDs travelling abroad are mainly related to chronic disease exacerbations, which mostly occur after the children return. Patients with diseases that require highly specialised care for an exacerbation should avoid travelling to resource-limited tropical countries.