Background and objectives Vitamin D deficiency is a global public health issue, which affects people of all ages and ethnicities. However, severe deficiency seems to be more prevalent in the Middle East and South Asia. Evidence suggests that low serum 25-hydroxycholicalciferol [25(OH)D] levels are associated with an increase in parathyroid hormone (PTH). Yet, the 25-OHD levels leading to serum PTH increase are still a matter of debate. The objective of this study is to assess deficiency of vitamin D in otherwise healthy individuals, and to determine the response of the PTH to vitamin D deficiency. Methods This observational study was conducted from January 2018 to May 2018. A total of 43 individuals were selected from three separate clinics in Libya (Alrazy clinic, Alhaya clinic, and Alnukbah clinic). Blood drawn from these individuals was assessed for serum calcium, phosphorus, 25(OH)D, and PTH. These data were collected and analyzed using the Statistical Package for Social Sciences (SPSS) version 17.0 for Windows (SPSS Inc., Chicago, IL). Results The mean age and standard (SD) of the study participants was 47.4 ± 12.4. The age range was 19-67 years. The ratio of male to female was 1:2. The percentage of individuals with vitamin D deficiency in the study group was 95.3%, whereas the percentage of vitamin D insufficiency was 4.7%. These data suggest that individuals with severe deficiency show higher PTH values (75.66 ng/ml), whereas those with insufficiency showed lower PTH values (37.5 ng/ml). Conclusion The population in the present study was overall deficient in 25-OH vitamin D, which indicates a greater need for supplementation with vitamin D. However, not all the individuals with vitamin D deficiency have high levels of PTH, a finding that agrees with the need for new criteria in the management of vitamin D deficiency and the importance of PTH testing.