The objective of the current study was to quantify the adherence property of Candida species causing infections in head and neck cancer patients on radiation therapy (RT) or chemoradiotherapy (CRT). Additionally, the study aimed to establish a correlation between adherence properties and patients’ hemograms. A prospective cohort study was done on head and neck cancer (HNC) patients with oropharyngeal candidiasis. All patients received radiation doses ranging from 60 to 70 Gy using Intensity Modulated Radiation Therapy. Inoperable patients received concurrent chemotherapy with cisplatin 40mg/m² once weekly during the course of RT. Swabs were collected from patients with signs and symptoms of candidiasis and microbiological confirmation and speciation were done according to standard protocol. An in vitro adherence test was done. Hemogram of all the patients at the start of infection was compared with the adherence. Candidiasis was detected in 58(35.3%) out of a total of 164 patients (Age 36-85). Candida albicans was the most prevalent 39(67.2%) species isolated. C.albicans showed the highest adherence which was statistically significant. The hemogram at the start of treatment and with C. albicans infection showed a statistically significant decrease in the absolute lymphocyte count (p-value 0.0001), RBC count (p-value 0.004) and haemoglobin level (p-value 0.003). Less adherence was seen with non-albicans Candida infection when compared to C.albicans (Odds 0.894, 95% CI -0.818-0.977), significant at 5 % (0.013). C. albicans showed significant adherence, which indicates the severity of infection. The occurrence of oral candidiasis is strongly associated with low lymphocyte count and severity of mucositis. Absolute lymphocyte count needs to be monitored in HNC patients who are undergoing RT or CRT.