Background: Although the literature indicates that patient delays in seeking medical support for Middle East respiratory syndrome coronavirus (MERS-CoV) infections are associated with poor clinical outcomes, delays in the diagnosis itself remain poorly understood in these patients. This study aimed to determine the median time interval from symptom onset to a confirmed diagnosis and to identify the potential predictors of this interval in Saudi Arabian MERS patients. Methods: This was a retrospective study of patients with confirmed MERS who were publicly reported by the World Health Organization (WHO). Results: Five hundred and thirty-seven symptomatic cases of MERS-CoV infection were included. The median time interval between symptom onset and confirmation of the MERS diagnosis was 4 days (interquartile range 2–7 days), ranging from 0 to 36 days. According to the negative binomial model, the unadjusted rate ratio (RR) of delays in the diagnosis was significantly higher in older patients (>65 years) (RR 1.42), non-healthcare workers (RR 1.74), patients with severe illness (RR 1.22), those with an unknown source of infection (RR 1.84), and those who had been in close contact with camels (RR 1.74). After accounting for confounders, the adjusted rate ratio (aRR) of delays in the diagnosis was independently associated with unknown source of infection (aRR 1.68) and close contact with camels (aRR 1.58). Conclusions: The time interval from symptom onset to diagnosis was greater in older patients, non-healthcare workers, patients with severe illness, patients with an unknown source of infection, and patients who had been in close contact with camels. The findings warrant educational interventions to raise general public awareness of the importance of early symptom notification.