Background: Lung cancer and cervical cancer are higher in incidence for Indigenous Australians and survival is worse compared with non-Indigenous Australians. Here we aim to determine if being Indigenous and/or other factors are associated with patients receiving “suboptimal treatment” compared to “optimal treatment” according to clinical guidelines for two cancer types. Methods: Data were collected from hospital medical records for Indigenous adults diagnosed with cervical cancer and non–small cell lung cancer (NSCLC) and a frequency-matched comparison group of non-Indigenous patients in the Queensland Cancer Registry between January 1998 and December 2004. The two cancer types were analyzed separately. Results: A total of 105 women with cervical cancer were included in the study, 56 of whom were Indigenous. Indigenous women had higher odds of not receiving optimal treatment according to clinical guidelines (unadjusted OR 7.1; 95% CI, 1.5–33.3), even after adjusting for stage (OR 5.7; 95% CI, 1.2–27.3). Of 225 patients with NSCLC, 198 patients (56% Indigenous) had sufficient information available to be analyzed. The odds of receiving suboptimal treatment were significantly higher for Indigenous compared to non-Indigenous NSCLC patients (unadjusted OR 1.9; 95% CI, 1.0–3.6) and remained significant after adjusting for stage, comorbidity and age (adjusted OR 2.1; 95% CI, 1.1–4.1). Conclusions: The monitoring of treatment patterns and appraisal against guidelines can provide valuable evidence of inequity in cancer treatment. We found that Indigenous people with lung cancer or cervical cancer received suboptimal treatment, reinforcing the need for urgent action to reduce the impact of these two cancer types on Indigenous people.