The laboratory network of the Gulab Devi Teaching Hospital has evolved from a small setup established since its inception in 1934 to a well-developed laboratory network encompassing all areas of health-care diagnostics aligning with the health services offered by the hospital with state of art equipment and standardized tests. 

The main laboratory started with a small setup with basic tests. In 1989, a separate purpose-built lab was constructed with a covered area of 3937 sq. feet, with an increase in the range of the offered tests. This laboratory has now developed into a diagnostic center with purpose-built separate sections of blood bank and haematology, chemical pathology and microbiology, and a main Haematology Lab with automated analyzers. In the chemical pathology department, manual tests are replaced by the state-of-the-art semi- and fully automated chemistry and immune-assay analyzers. 

The laboratory has a fully functional blood bank with a covered area of 520 sq. feet certified by the Punjab Blood Transfusion Authorities. The laboratory is serving patients 24 hours, seven days a week.

The Microbiology Laboratory initially provided basic tests like smear microscopy and culture. A purpose-built laboratory for tuberculosis diagnosis was built in 2002 and further extended in 2009 to cope with the increasing work load. This laboratory evolved over the years into a reference laboratory with all World Health Organization endorsed tests for tuberculosis diagnosis, provided free of cost to all presumptive tuberculosis patients seeking care at the hospital. This works in collaboration with national and provisional TB programs and undergoes regular external quality control by national and provisional TB programs to ensure standardization of diagnosis.

Histopathology examination for tissue samples was at first out-sourced; however, with the increase in the work load, and aim to deliver free of cost services to the admitted patients, a small Histopathology Laboratory was established in 1990. Initially, this lab offered basic tests and was housed in an already existing research center. Later a purpose-built Histopathology Lab was completed in 2016, with an increase in the number of qualified histopathologists. Immuno-staining started in 2017, and the frozen section in 2021. The lab is accredited for FCPS training. All sections are headed by qualified and experienced professors with a team of associate professors, assistant professors and medical officers.