Introduction Mannose-binding lectin (MBL) serum protein, is an important molecule of the innate immune system that is involved in antimicrobial recognition and clearing responses. There is no conclusive evidence that MBL deficiency is associated with adverse respiratory consequences. Aim We explored whether there is a difference in clinical, radiological and microbiological characteristics in children with MBL deficiency presenting with troublesome respiratory symptoms (frequent, recurrent, persistent or very severe), as compared to those who are MBL-sufficient. Methods We performed a retrospective study looking at MBL measurements in children over a period of 10 years in a large teaching hospital, with a minimum follow-up period of 5 years from the time of the MBL measurement to the year 2019. Results 32% of children with MBL deficiency and 30% of those with MBL sufficiency had positive microbiology. 23% of children with MBL deficiency and 24% of those with MBL sufficiency had radiological changes on plain radiographs. 28% of children with MBL deficiency and 33% of those with MBL sufficiency had suboptimal vaccine responses to primary immunisations. 67% of the MBL-deficient children had suboptimal vaccine responses to booster immunisations, compared to 40% of the MBL-sufficient group. Conclusion We conclude that there is no difference at five year follow-up in clinical, radiological and microbiological characteristics between children who are MBL-deficient as compared to those who have sufficient levels. These results add to the existing body of literature that shows no statistically significant association between MBL deficiency and susceptibility to recurrent respiratory tract infection in children.