The quality of healthcare services in every society has been a dire need across each era. The effective implementation of which is only possible if the healthcare workers get provided with a suitable environment to perform their duties in. Considering this, the current study determines the impact of internal marketing on the quality of external services delivered to the patients in the labor-intensive healthcare industry of Pakistan. Further, the mediatory role of internal service quality between the said variables is taken into account. The survey-based study was conducted in the twin metropolitans of Pakistan (Islamabad & Rawalpindi). The collected data from 500 individuals comprised of internal customers i.e. doctors, staff members, and external customers i.e. patients, of the public sector as well as private sector hospitals. The study conclusively suggested a significantly positive impact of internal marketing over the external service quality; in both service sectors. Though the public-sector healthcare organizations were found to be comparatively more effective in the implementation of service quality delivered to its customers, in contrast to the private sector healthcare institutions.