Background: Puerto Ricans are among the largest Hispanic groups in the US. Clinicians/researchers must become skilled in assessing the prevalence of the perceived unmet needs of Puerto Rican cancer patients undergoing treatment to properly respond to their needs, and is an important part of any culturally comprehensive oncological care. Objective: To assess Puerto Rican cancer survivors reports of perceived unmet needs across 5 domains of the cancer experience: "psychological", "health system and information", "physical and daily living", "patient care and support", and "sexuality" and to examine how the perceived unmet needs and disease characteristics are inter-related. Methods: A cross-sectional survey was conducted from 103 patients (64.1% female, male 35.9%, mean age 54 years) undergoing cancer treatments. The study participants were >20 years of age with breast (28%), gynecologic (21%), prostate (17%) and gastrointestinal (14%) cancer, mostly on chemotherapy. Overall internal consistency of the Supportive Care Needs Survey was 0.882. Results: Patients perceived needs were highest in the domains of sexuality (67%), physical and daily living (55.3%), and psychological (38.8%). Breast cancer was significantly related to reporting unmet needs in the domains of health services/information (p = .018) and sexuality (p = .009). Prostate cancer showed a significant relationship with unmet needs in the domains of psychological (p = .050) and, the physical/daily living (p < .001). Receiving chemotherapy was related with unmet needs in the domains of sexuality (p = .02), and the physical/daily living (p = .047); and, receiving combination of radiation and hormonal therapy was related to unmet needs in the physical/daily living needs domain (p = .024). Conclusions: The accurate assessment of supportive care needs is important in the management of cancer patients. The unmet supportive care needs of our sample of Puerto Rican cancer patients seem to be affected by cancer site and treatment modality.