BACKGROUND: The Hajj is one of the world's largest pilgrimage and gathers millions of Muslims from different nationalities every year. Communicable diseases have been reported frequently, during and following the Hajj, and these have been linked to individual behavioural measures. This study aimed to measure the effect of personal preventive measures, such as face mask use, hand hygiene and others, adopted by pilgrims in reducing the acquisition of infectious diseases. METHODS: We conducted a cross-sectional study at the Hajj terminal in King Abdulaziz International Airport in Jeddah, Saudi Arabia. Pilgrims were approached in the airport lounges after the 2017 Hajj season and prior to the departure of their flights from Jeddah to their home countries. An electronic data collection tool ('Open Data Kit') was used to gather survey data in regards to health problems and preventive measures during the Hajj. RESULTS: A total of 2973 Hajj pilgrims were surveyed. In all, 38.7% reported symptoms of upper respiratory tract infections (URTIs) and 5.4% reported symptoms of travel diarrhoea. Compliance with face mask use was 50.2%. Changing a face mask every 4 h was found to be significantly associated with lower prevalence of URTIs [adjusted odds ratio 0.56 (95% confidence interval 0.34-0.92), P = 0.02]. There was no statistical difference between overall face mask use and URTI acquisition. The main sources of food, eating raw vegetables/food, frequency of hand washing or use of hand sanitizers were not found to be significantly associated with reported travellers' diarrhoea. Unlicensed barbers were used by 12% of pilgrims and 9.2% of pilgrims reported using blades that were reused by other pilgrims. CONCLUSION: Preventive measures are the most effective way to prevent infections. Pilgrims can benefit from face masks by changing them frequently. There is still limited information on the effect of the use of face mask in decreasing the risk of URTI in mass gatherings.