Changes in erythrocyte parameters are well known in both beta-thalassemia minor (BTM) and iron deficiency (ID) when either is present alone; however, to our knowledge, there has been no study showing the changes when the two conditions coexist. We herein assessed erythrocyte parameters in BTM with coexistent ID. The BTM cases were divided into two groups based on ferritin levels as ID+ and ID-; the ID+ group was then further divided based on hemoglobin (Hb) levels as iron-deficient carriers with (IDA+) and without (IDA-) anemia. When compared to the ID- group, all parameters were significantly different in the IDA+ group except mean corpuscular volume (MCV) and red blood cells (RBC). All parameters except RBC were significantly different between the IDA+ and IDA- groups. Hb, hematocrit (Hct), MCV, and mean corpuscular hemoglobin (MCH) levels in the IDA- group were found to be lower than in the ID- group. Changes in erythrocyte parameters in iron-deficient carriers are critical in screening for BT, particularly for correct formulation of mathematical algorithms utilized by artificial intelligence programs.