Background: The health of the caregivers is crucial to sustain informal care provision, while multimorbidity is an important health risk concept. However, studies on the association between informal caregiving and physical multimorbidity are currently lacking. Therefore, we investigated this association in adults from 48 low- and middle-income countries (LMICs).; Methods: Cross-sectional data from 242,952 adults (mean age 38.4 years) participating in the World Health Survey 2002-2004 were analyzed. Informal caregivers were considered those who provided help in the past year to a relative or friend (adult or child) who has a long-term physical or mental illness or disability, or is getting old and weak. Nine physical conditions were assessed. Multivariable logistic regression analyses were conducted to assess associations between informal caregiving and physical multimorbidity, while the between-country heterogeneity in this relationship was studied with country-wise analyses.; Results: The overall prevalence of informal caregiving and physical multimorbidity (i.e, ≥2 physical conditions) was 19.2% and 13.2%, respectively. Overall, caregivers had 1.40 [95% confidence interval (CI)=1.29-1.52] times higher odds for physical multimorbidity. This association was particularly pronounced in younger caregivers [e.g., 18-44 years: odds ratio (OR)=1.54; 95%CI=1.37-1.72], while this association was not statistically significant among those aged ≥65 years (OR=1.19; 95%CI=0.98-1.44). Country-wise analyses corroborated these findings and there was a negligible level of between-country heterogeneity (I2=24.0%).; Conclusions: In LMICs, informal caregivers (especially young caregivers) were more likely to have physical multimorbidity. This should be taken into account in policies that address the health and wellbeing of informal caregivers.